ORNL-TM-3939

Y

i

ORNL-TM-393Y

MSR COMPONENT REPLACEMENTS USING REMOTE CUTTING AND WELDING TECHNIQUES , I *

r, _. < ’

Peter P. Holm

This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that i t s use would not infringe privately owned rights.

ORNL- TM- 3939

C o n t r a c t No. W-7405- eng- 26

R e a c t o r Division

HSR COMPONENT REPLACEMENTS USING REMOTE CUTTING AND WELDING TECHNIQUES

Peter P. Holz

December 1972

OAK RIDGE NATIONAL LABORATORY O a r Ridge; Teniessee 37830

operated by UNION CARBIDE CORPORATION

for t h e U.S. ATOMIC ENERGY COMMISSION

N O T I C E This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commissron, nor any of their employees, nor any of their conlractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness o r usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. _._ _ _ _ ~ _

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CONTEXTS

Page

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y LI

. W

1 . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 . CONCLUSIONS AND SUMMAIIY . . . . . . . . . . . . . . . . . . . . . 6

3 . STATUS OF THE TEC3l!OLOCN . . . . . . . . . . . . . . . . . . . . 7

3.1 Cel l I l lmir ia t ion . . . . . . . . . . . . . . . . . . . . . . 7

3.1.1 Ligh-Ling Frovisions fo r Maintenance . . . . . . . . . 7

3.2 In-Cell Viewing Apparatus . . . . . . . . . . . . . . . . . 7

3.2.1 Direct Viewing Through Lead Glass o r Zinc- Bromide Wimdows . . . . . . . . . . . . . . . . . . . 7

3.2.2 Optical Equipment: Mirrors. Periscopes. and Fiber Optics . . . . . . . . . . . . . . . . . . 8

3.2.3 Closed Circuit Television . . . . . . . . . . . . . . 9

3.2.4 Special Irlspections . . . . . . . . . . . . . . . . . 10

3.3 In-Cell Handling Tools . . . . . . . . . . . . . . . . . . . 10 3.3.1 Li f t ing Devices . . . . . . . . . . . . . . . . . . . 10 3.3.2 Miscellaneous Long-Handled Tools . . . . . . . . . . 10 3.3.3 Portable Eetaining Brackets . . . . . . . . . . . . . 11 3.3.4 Thermocou-@e and Electrical Connector Tools . . . . . 11

3.4 Tool and Equipment Conveyance Means . . . . . . . . . . . . 11 3.5 Pipe Cutting Equipment . . . . . . . . . . . . . . . . . . . 12

3.5.1 Pipe Cutters . . . . . . . . . . . . . . . . . . . . 12

3.5.2 Seal Weld Cutters . . . . . . . . . . . . . . . . . . 20

3.6 Equipment f o r Pipe Spreading . . . . . . . . . . . . . . . . 25

3.7 Carriers and Conveyance Means f o r Use Within t h e Cel l . . . 25

3.8 Carriers f o r Use (Outside t h e Cel l . . . . . . . . . . . . . 25

3.9 In-Cell Preparations for Equipment Reinstal la t ion . . . . . 26

iv

. 3.10 In-Cell Cleanliness Control . . . . . . . . . . . . . . . . 26 3.11 Conveyance of Components to Reinstallation Location . . . . 27 3.12 Pipe Alignment Technology . . . . . . . . . . . . . . . . . 27 3.13 Weld Preparation and Tack Welding of Pipe Joints . . . . . 31 3.14 Closure Welding . . . . . . . . . . . . . . . . . . . . . . 34

3.14.1 Pipe Welding . . . . . . . . . . . . . . . . . . . 34 3.14.2 Seal Welding . . . . . . . . . . . . . . . . . . . 37

3.15 Inspection and Acceptance Tests . . . . . . . . . . . . . . 40 APPENDIX A

Calculations f o r Anticipated Maximum Delections and Restoration Forces for Cutting INOR-8 Piping Material . . . . . . 43

APPENDIX B

1) Proposal for Development of a Split-Bearing-Sleeve Carriage for Remote Maintenance Applications in Nuclear Reactor Systems . . . . . . . . . . . . . . . . . . . 4.9

2 ) Manufacturers Information on Split-Roller Bearings . . . . . 55

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

W ILLUSTRATIONS

Page

Fig . 1 . Typical Replacenient Joint Location . . . . . . . . . . . . 5

.

Fig . 2 . ORNL Cutter o r Machining Head Module . . . . . . . . . . . . 13

Fig . 3 . ORNL Orbi ta l Cutting Equipment . . . . . . . . . . . . . . . 14

Fig . 4 . Seal P la t e Welds . . . . . . . . . . . . . . . . . . . . . . 21

Fig . 5 . Sandwich Seal Weld . . . . . . . . . . . . . . . . . . . . . 22

Fig . 6 . Canopy Weld Schemes . . . . . . . . . . . . . . . . . . . . . 23

Fig . 7 . Seal Lip Closures . . . . . . . . . . . . . . . . . . . . . . 24

Fig . 8 . Component Pipe Stub Weld Joint Posit ioner Arrangement . . . . 29

Fig . 9 . Pipe Alignment J:ig f o r Line Cutting and Welding . . . . . . . 29

Fig . 10 . ORNL Orbi ta l Welding System . . . . . . . . . . . . . . . . . 35

Fig . 11 . Equipment Hook.Up, ORNL Weld System . . . . . . . . . . . . . 36

Fig . 12 . Conceptual Diaphragm o r Sandwich Seal Weld with ORNL Weld Head Supported from a Motorized Carousel Linkage . . . . 38

Fig . 13 . Flanged Vessel Seal Weld Closure Scheme f o r Orbi ta l System Inser t s . . . . . . . . . . . . . . . . . . . 39

Fig . 14 . Conceptual Design . . . . . . . . . . . . . . . . . . . . . . 41

........ Table 1 . Expected Life of Cutter Blades . . . . . . . . . . . . . . . 16

v i i

W MSR COMPONENT REPLACEMENTS USING REMOTE CUTTING

A!7D WELDING TECHNIQUES

P. P. Holz

ABSTRACT

In molten s a l t I-eactor systems t h e maintenance of components i n high- rad ia t ion zones w i l l be accomplished by using remotely operated tools. System components, such a:; pumps, heat exchangers, and valves w i l l be ex- changed by cu t t ing t h e in:l.et and ou t l e t pipe connections, replacing t h e component, and welding t h e pipe by remote means.

Remote maintenance requires special equipment f o r viewing and close inspection of equipment arid systems inside t h e c e l l t o determine what i s wrong; it a lso requii-es syecial apparatus t o convey tools t o t h e place where work i s t o be performed. w i l l be severing t h e pipe and other connections, spreading t h e pipe ends t o provide clearance f o r removing t h e component, conveying t h e component from i t s locat ion ins ide t h e c e l l i n to a shielded car r ie r , and t ransport ing t h e c a r r i e r outside. w i l l involve t h e s teps of maintaining cleanliness control, conveying t h e replacement equipment, t o its c e l l location, realigning t h e component and t h e pipe ends f o r reassembly, tack welding t o hold components i n place during f i n a l closure welding, and then performing t h e inspection and acceptance checks t o assure that, t h e repa i rs have met qua l i ty and r e l i a b i l i t y standards. Seal weld cu t t ing and rewelding may be required f o r some vessel enclosures.

The main steps i n remote maintenance procedures

ReinstaLling a new component t o replace t h e one removed

Overall system maintenance planning t o precede future la rge sca le molten s a l t breeder reactor const;ruction by industry i s envisioned as a four-stage evolut ia:

1)

2 )

3 )

4 )

Technology study a- consideration of remote maintenance requirements

Simulation t e s t mockups - component tests under simulated reactor

General engineering reactor project mockups - t es t s i n reactor

Small demonstration reactor - t e s t s under ac tua l reactor conditions.

i n conceptual design

conditions

system mockups

Accordingly, t h i s report i s intended t o serve as a useful program out- The report describes i n d e t a i l how we intend t o perform remote l i n e guide.

maintenance within t h e sevlwe in-ce l l radiat ion and temperature environments. It a lso describes t h e current s t a tus of t h e technology required t o perform each remote maintenance task, giving spec ia l emphasis t o t h e f'unctions we need t o perfect on a f i r s t order pr ior i ty : remote cutting, welding, and posit ioning device development. mended t o provide a l l of t h e needed remote-control devices t o demonstrate complete maintenance procedures f o r removing and replacing a l l types of components i n t h e high-radiation, high-temperature zones within t h e reactor

Additional development programs a re recom-

v i i i

W shielding. The " s t a t e of t h e a r t " fo r many of t h e functional tasks such as viewing, l ight ing, component and equipment movement and t r ans fe r i s already adequate f o r remote control operations, and hence w i l l not require special e f fo r t s a t t h i s time.

1.0 INTRODUCTION

After reactor operations a t high-power l eve l s have b u i l t up t h e radia- t i o n leve ls i n t h e shielded c e l l s containing t h e nuclear system components, t h e problems of mairitenarice and repa i r become more d i f f i c u l t and more i m - portant. No reac tor i s 2-mmune t o these problems. The need f o r remote tooling and apparatus t o cut, bevel, and weld piping i n high-radiation l e v e l zones i s of utmost i.mport;ance f o r t h e replacement of reactor components t ha t have f a i l e d i n service.

Exact specif ica.t ions to cover ant ic ipated temperatures and rad ia t ion and contamination l eve l s i n t h e molten-salt reactor c e l l a t t h e time of a maintenance shutdom. a r e not as yet available, but t en ta t ive estimates a re given i n R. W. McClung's report on "Remote Inspection of Welded Joints. ' ' '

"Anticipated temperatures i n t h e reactor c e l l range from 1000 t o 1200°F. However, local ized cooling f o r both welding and inspection can probablgr br ing temperatures down t o t h e range 200 t o 600°F and possib1;y even t o 200 t o 400°F.

The ant ic ipated l e v e l of radiation3' i n t h e reactor c e l l t e n days a f t e r t h e system i s shut down and drained i s expected t o be approximately lo5 R/hr . gamma rays from re l a t ive ly noble f i s s i o n products deposited on t h e metal surfaces 0.f t h e heat exchanger tubes and on t h e graphi te i n t h e core vessel. (calculated t o be l.d& X lo5 R/hr) i s a t t h e midplane immediately adjacent t o a heat exchanger. Values i n other portions of t h e c e l l may be 25 t o 30$ of t h e maximum. w i l l have photon energies of 0.8 MeV and below."

The dominant radiat ion w i l l be

The area of highest dose r a t e

Most o f t h e radiat ion

The elevated c e l l temperatures and rad ia t ion leve ls eliminate any poss ib i l i t y of personnel access in to t h e c e l l f o r any d i rec t work whatever on molten s a l t breeder reactor maintenance. It w i l l be e s sen t i a l t h a t a l l work be done remotely.

It i s planned t o replace a component by severing i t s pipe connections, rebeveling t h e ends of t h e in-ce l l piping, aligning t h e beveled ends with those of t h e replacement, and rewelding t h e component i n to t h e system, a l l by t h e use of remote-cont 1-01 equipment. Adequate viewing, inspection, pipe spreading, and pipe :3ligmiient equipment must also be avai lable and demon- s t r a t ed t o be operable by remote control t o support t he bas ic operations of remote cu t t ing and rewelding.

Best estimates now indica te t h a t Hastelloy, Inconels, or special 300 se r i e s s t a in l e s s s t e e l alloys, w i l l be used f o r a l l t h e salt-containing pipe and component materials f o r molten s a l t breeder reactors. a r e expected t o range from 1 t o 20 inches and pipe wal l thicknesses from 1/4 t o 1 inch. vesse l w i l l be i n t h e order of 5 f e e t and 30 f e e t respectively. mary system metal select ions add a number of res t r ic t ions t o common repair t o o l and lubricant mater ia l selections. alloys, and no sulfw-beasr.ing o i l s can be used where they might possibly

Pipe s izes

Cylindrical diameters fo r t h e heat exchangers and core The pr i -

No aluminum or other low-melting

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contact Hastelloy N, because these materials may react t o cause a loss of desired Hastelloy N properties. Similarly, f o r s t a in l e s s s tee ls , chlorine-free materials must be used.

Semi-remote maintenance i s t h e preferred and safes t approach because it reduces personnel rad ia t ion exposures and s implif ies t h e problems of decontamination p r io r t o undertaking nuclear r epa i r operations. However, t h e a b i l i t y t o perform maintenance by remote control requires t h a t t h e reactor system be designed t o provide access t o a l l components, t o allow f o r conveyance of t oo l s and equipment within the c e l l areas, and t o provide a l so f o r t he storage of contaminated repa i r t oo l s and re la ted equipment when they a r e not i n use. The reactor designers, s t r e s s analysts, and reactor maintenance engineers must confer during a l l design stages t o be sure t h a t clearances a re adequate f o r maintenance access and equipment replacement and t h a t t h e layout of pipe-runs and components, with provisions f o r support and expansion, represents t h e optimum compromise between maintenance needs and nuclear materials inventory i n t h e system.

It i s recognized t h a t providing f o r remote-control removal and replacement of a l l components of a reactor system would be prohibi t ively expensive. In practice, therefore, t h e degree of ease provided f o r remote maintenance must depend upon the ant ic ipated frequency of maintenance fo r each component. Pumps, (par t icu lar ly t h e ro ta ry pump elements, t h e j e t pumps used f o r f i l l i n g t h e s a l t system, and t h e j e t pumps used i n conjunction with t h e gas separators), valves, heat exchanger bundles, samplers, and other items may f a i l o r need maintenance more frequently than, say, t he reactor vessel, which i s designed f o r a 30-year maintenance-free l i f e . A higher ant ic ipated frequency of maintenance could j u s t i f y r a the r elaborate remote-control devices t o speed up and make more r e l i a b l e t h e operations of repa i r or replacement.

There is, however, a degree of uncertainty i n predict ing t h e locat ions a t which one should be prepared t o make repa i rs by remote control. duce the r i sk of having t h e reactor system shut down a long time f o r r epa i r and maintenance, general purpose devices should be readied a t t h e outset t o handle unexpected repa i r operations i n v i r t u a l l y a l l locat ions with minimum delay. The codes f o r in-service inspection of nuclear reactor systems re- cognize the problem of examining radioact ive areas where human access i s impossible and suggest t h a t it w i l l be necessary t o devise and develop methods f o r t h e inspection of vessels, pipe, and equipment t o detect flaws by remote means. There i s a general need f o r remote handling, posit ioning, cutt ing, and welding equipment with which t o r epa i r t h e flaws disclosed. One could conceivably adapt t h e inspection equipment f o r applica- t i o n with repa i r work.

To re-

It can be seen from t h e above t h a t replacement and ce r t a in in-place repa i rs of radioact ive components involve t h e capabi l i ty t o perform a number of sequential s teps o r functions many of which a r e essent ia l ly t h e same f o r most components. The equipment t o perform these functions can be developed generally, independent of t h e spec i f ic d e t a i l s of a pa r t i cu la r reactor design, i f t he reactor design i s developed with adequate a t ten t ion t o t h e requirements of remote maintenance and of t h e remotely controlled

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equipment. If, i n some cwes, t h e provisions f o r t h e performance of a pa r t i cu la r function r e s t r i c t s t h e designer too much, a modified piece of equipment may have t o be developed concurrent with t h e reactor design phase. It i s recommended, tlnerefore, t h a t maintenance development f o r each of t h e four stages of evolution proceed along t h e following general pattern:

I. Technology study

1. Prepare a general survey of maintenance needs of a reactor system based on a general design concept.

2. During t h e concepi:,ual design stage, plan how t h e maintenance of each of t h e radios.ctive components of a reactor system w i l l be performed.

3. From t h e remote ma.intenance plans, determine t h e functions needed and se lec t f o r study those functions f o r which there i s l i t t l e o r no previous experience.

4. Conduct s tudies t o i d e n t i e r e s t r i c t ions which each function may place on t h e reactor design. Work with the reactor designer t o provide for maintenance operations i n t h e design of t h e reactor system equipment arrangement

11. Simulation t e s t mockups

1. Proceed with t h e development of equipment to perform t h e various functions and, with t h e demonstration i n a mockup designed t o simu- l a t e features of t,he reactor system. Alter t h e d e t a i l s of t h e equipment design m d t h e reactor design as required t o minimize inconvenience, increase safe ty and r e l i a b i l i t y , reduce cost, or provide f o r other considerations which may be s ignif icant .

111. General engineering reactor project mockups

1. Prepare fo r , and carry out t h e demonstration of t h e remote maintenance plan, including a l l of t h e functions, i n a reactor mockup. Perfect t h e detai led procedures and check l i s t s .

2. Acquire and t e s t a l l of t h e equipment needed f o r maintenance of t h e ac tua l reactor system.

IV. Small demonstration reactor

Use a s much of t h e maintenance equipment as i s necessary during t h e reac tor system construction phase t o assure t h a t t he re have been no changes i n t h e design which would compromise t h e maintenance plan.

We have already provein t h e remote cu t t ing and welding operations on pipe t o be f eas ib l e with adequate piping supports f o r cutting, and with near precision pipe end realignment f o r welding. Limited s tudies made on how to support and real ign in-ce l l reactor piping revealed many new problem areas and uncertaint ies , and pointed out urgent needs f o r developmental

4

experimentation before one can proceed t o develop apparatus, equipment, and techniques f o r t h i s work. We, therefore, recommend t h a t t h e next s t ep be a more thorough technology study along with mockup t e s t s t o es tab l i sh pipe springback allowances and pipe realignment tolerance requirements. Cutting and welding machinery can the rea f t e r be adapted t o meet t h e best pipe support and posit ioning c r i t e r i a we a r e able t o establish. We suggest a new review of automated commercial pipe cu t t ing and welding equipment f o r t h a t time. The indus t r i a l development of such machinery i s presently proceeding a t a f a s t pace; therefore, automated cu t t ing and welding equipment should become readi ly avai lable from commercial sources f o r adaptions f o r our work with reactor maintenance tasks.

In t h i s report we have used t h e reference design f o r t h e s ingle f l u i d molten-salt breeder reactor =to determine t h e need f o r t h e component replacement capabi l i ty and have developed a remote maintenance plan for t h e replacement of t yp ica l componentso t h e ORNL maintenance technology employing an o r b i t a l carr iage which clamps onto a pipe t o propel t h e cu t t ing andlor welding heads around t h e circumference of a pipe, while a programmer-controller automatically controls t h e operations involved i n pipe cutting, beveling, and welding. For the cut t ing and welding of flange sea ls or sea ls of other types, we plan t o u t i l i z e t h e same or similar equipment, except f o r t h e carr iage and carr iage drive. Many s e a l closure designs a re available; t h e report i l l u s t r a t e s and discusses t h e maintainabili ty of several t yp ica l con- f igurat ions. t i a l s teps or functions which a re needed t o carry out a maintenance plan and discusses b r i e f l y t h e s ta tus of equipment and operating experience f o r each of t h e functions. The fu ture development requirements f o r remote maintenance equipment a r e described including some cost estimates and suggested p r i o r i t i e s . This report includes recommendations from our pipe alignment studies i n Appendix A, and suggests piping arrangements f o r simplified maintenance, Figure 1 i l l u s t r a t e s t h e recommended mounting of components f o r ease of replacement. ment j o in t can be predesignated and supports provided so t h a t t h e pipe spreading and realignment requ-frements can be handled i n grea t ly simpli- f i ed fashion using standard threaded, hydraulic or pneumatic jacking equipment. Schemes" and Appendix B, "Proposal f o r t h e Development of a Split-Bearing- Sleeve Carriage f o r Remote Maintenance Applications i n Nuclear Reactor Systems, I' both discuss t h e highly important subject of equipment and pipe alignment i n more d e t a i l and suggest development experfmentat ion with sleeves t o s implim remote maintenance operations, a t l e a s t fcr t h e smaller pipe s izes .

The plan i s generally based on

The "Status of t h e Technology" sect ion describes t h e sequen-

The locat ion f o r t h e replace-

Section 3,12.1.1 of t h e "Experience Status - Pipe Alignment

This report does not include detai led recommendations f o r t h e development of special materials for construction f o r t h e maintenance equipment t o meet t h e contemplated high temperature and high rad ia t ion service requirements. A study should be performed t o determine t h e maximum temperature and radiat ion in tens i ty t o be expected within t h e reactor c e l l s and t o estimate t h e addi t ional research and development needed t o se lec t and t e s t materials t h a t w i l l stand up under these conditions.

5

C

ALIGNWNT kQLIIPMHT NOT S H O W

Fig. 1. S p i c a 1 Replacement Jo in t Location

6

2.0 CONCLUSIONS AND SUMMAHY

For t h e sake of completeness, we have included i n t h e report a descrip-

Many of these, such a s l ight ing, t i o n of t h e equipment and technology f o r performing a l l of t h e functions needed f o r t h e replacement of a component. viewing, and component and maintenance equipment movement r e f l e c t t h e benefi t of extensive experience gained during t h e operation of t h e HRT, E R E , and other reactor projects. and require essent ia l ly no development study before a reactor grade item could be designed.

We bel ieve t h a t they a re adequately understood

There a re other functions such as carr iage o rb i t propulsion, pipe cut t ing and welding, which have received only l imited evaluation f o r possible application t o molten s a l t reactors i n connection with our work on t h e o r b i t a l pipe welding system with programmed automated cutt ing, beveling, and welding accessories. 239 25 ment of an automated pipe welding system which i s now being used by t h e Tennessee Valley Authority i n t h e i r Browns Ferry fluclear Plant construction, and which has served as a prototype and pa t te rn f o r t h e un i t s t o be used i n t h e Fast Flux Test F a c i l i t y a t Hanford. The development of an indus t r i a l capabi l i ty f o r t h e production of t h e automated welder increases our confidence t h a t t h e equipment, a f t e r modification f o r t h e environment and f o r t h e remote operation, w i l l perform t h e functions needed f o r reactor component replacement. However, t he re a r e some aspects o f t h e modifications needed t o permit remote operation for which fur ther study would help i n optimizing t h e equipment design. We would reevaluate t h e automated welding equipment which has become avai lable commercially s ince t h e s t a r t of our e a r l i e r welding program, choose t h e one which best s u i t s our needs, modify as necessary, and t e s t it under conditions simulating some of those expected i n a reactor system. We would expect t h a t t h e bas ic equipment for development and t e s t i n g would be b u i l t from standard l i n e materials and t h a t subs t i t u t e materials would not be needed a t t h i s time.

These s tudies l ed t o t h e develop-

The urgent function for which phas I s tudies and phase I1 s:;nulation

We a re proposing t h a t would be helpful t o t h e ear ly phases of a reactor project i s t h a t of pipe and component alignment i n preparation f o r welding. where possible t h e pipe be made f l e x i b l e enough t o permit t h e necessary displacement needed f o r proper alignment. described i n Appendix "A" ind ica te t h a t f o r most pipe s izes t h i s would be a p rac t i ca l approach. pipe length does not permit much f l e x i b i l i t y , we a r e proposing t h a t a short sect ion of pipe be t a i lo red t o f i t between t h e misaligned pipe ends and t h a t it be welded i n place with t h e remote welder. 'indicated tha t t h e approach i s feasible , but we would l i k e t o gain some experience i n applying t h e w e l d e r t o such s i tuat ions. developing a gear-driven spli t-bearing-sleeve carr iage f o r possible maintenance applications i s included i n Appendix B. This more r i g i d carr iage would gain addi t ional torque capabi l i ty f o r pipe cu t t ing and beveling work, would be more readi ly adaptable f o r i n t e rna l pipe cleaning applications, and hopefully, would a l so simplify solutions t o alignment problems for small pipe s izes by serving t o minimize t h e displacement of pipe ends

displacement t-. l imi t s within tolerance ranges acceptable f o r rewelding.

Some preliminary estimates

For t h e very la rge pipes, or f o r cases where t h e

Our studies have

A proposal f o r

a f t e r being cut. The clamping of t h e carr iage might be enough t o hold t h e 1

7

McClungl has describ'ed t h e development necessary to provide equipment f o r performance of t h e inspection function and much of t h i s w i l l be accomplished during thle program f o r t h e in-service inspections of reactor vessels. We bel ieve t h a t t h e necessary t ransport function needed f o r moving t h e inspection equipment along t h e pipe welds can be obtained with t h e weld carriages. However, t h e influence of t h f s inspection function on t h e basic carr iage design should be evaluated before f i n a l carr iage design select ions a r e made.

In t h e future, during phase 111, t h e general engineering reactor project mockups, when it i s time t o t e s t t h e molten s a l t reactor system designs using semblance of t h e more complicated systems and components, it would be a great sdvanbage to be able t o perform remote maintenance t e s t s on t h e mockups. This w i l l help to assure t h a t t h e reactor system components i n t h e f i n a l design a re capable of being maintained. The sa t i s fac tory performance :If remote-handling devices, cleanliness control, and operating techniques can a l s o be proved i n mockup t e s t s , giving increased confidence i n t h e i r r e l i a b i l i t y and providing t r a in ing i n maintenance techniquI3s th:rt w i l l someday reduce downtime.

3.0 3TATUS OF THE TECHNOIOGY

3.1 Cell Illuminat ion

3.1.1 Lighting Provision:: f o r Maintenance

3.1.1.1

3.1.1.2

Experience. In t h e HRE, t h e HRT, aid t h e E R E , i n -ce l l l igh t ing proved adequate f o r repa i r purposes. 2 9 3 9 '' 5 ' F In tegra l Pi,;ghts on t h e underside of a portable shield provided su:oplemental i l lumination when required. The l i g h t s incli,ided dimmer controls, placed external t o t h e ce l l , to provide contrast and shadow effects . Portable, suspended l i g h t s were used as required to help d is t in- guish :;pecietl ob3 e c t s . Future -. DeveLopment Requirements . equipment t o be sure tha t select ions represent, t h e best current ly avai lable commercial equipment. Permanent in- c e l l wiring and l ight ing, i f used, should consistr of materials to , withstand c e l l radiat ion exposure leve ls of up t o t h e oi-der of 10llR and ambient c e l l temperatures of about 1_200"F, and up t o 1500°F f o r short periods.

Updat e t h e l i gh t ing

3 .2 :h-Cell Viewing Apparatus

3.2.1 Direct Viewing Through Lead Glass or Zinc-Bromide Windows

3.2.1.1 Current; Concepts. Direct viewing i s usual ly adequate for - unobstructed s t ra ight l ine-of-sight and general area ob- servati.ons. For reactor maintenance operations it, w i l l be necessa.ry t c ) provide gamma-ray shielding. Commercially

8

marketed lead-glass shield plugs and zinc-bromide windows a re commonly used and a re generally sa t i s fac tory f o r vision, i l lumination and shielding. Shield effectiveness i s gen- e r a l l y proportional t o density. Density values f o r major reactor shielding materials a r e as follows:

Concrete density about 2.2

" 7.8 11 Iron

I ' 2.7 I ? Aluminum

01 Lead 'I 11.3

I' 6.2 11 Lead Glass

q q 2.5 11 Zinc-Bromide Solution

Hence lead glass shield plugs have approximately 8% of t h e gamma shielding value of iron, and zinc-bromide windows provide approximately 10% b e t t e r shielding than concrete.

3.2.1.2 Experience. ORNL and others, including a l l hot c e l l operators, have had considerable experience with lead g lass and zinc-bromide f o r shielded viewing applications. Theoretical design information i s readi ly available7 and ac tua l select ion d e t a i l s a r e l i s t e d i n t h e design and operations reports f o r various nuclear i n s t a l l a t ions . 6 j

3.2.1.3 Future Development Requirements. None

3.2.2 Optical Equipment: Mirrors, Periscopes, and Fiber Optics

3.2.2.1 Definition. The use of mirrors t o a s s i s t d i r ec t viewing has proven helpful f o r many remote observations. Simple -&ilt-Li;KGges can be operated i n conj%ctlon with long handled too ls t o provide suf f ic ien t manipulations f o r adequately aligning t h e mirror f o r viewing. Commercially avai lable periscopes, omniscopes, telescopes , and f iber - opt ics equipment can be obtained t o meet a l l so r t s of needs i n nominal radiat ion and high-temperature environments, and have been used ef fec t ive ly i n reactor repa i r and i n hot c e l l work applications.

9

3.2

3.2.2.2 Experience. ORNL has varied experience with op t i ca l equip- The "blanket mirror viewing

-- ment i n numerous applications. device" and viewing scopes used i n conjunction with HRT core hole plugging operations2'9 , op$J.cal tool ing devices and periscopes used i n t h e MSRE6'8' , and t h e periscope used i n examiriatioris of t h e Boiling Nixflear Superheater Power Stat ion (BONUS) a t Rincon, Puerto Rico a r e examples of apparatus used i n some of ORNL's remote viewing experiences. on nuclear vessel repa i rs a t Savannah River12 l i s t s some of DuPont's op t i ca l too l ing experiences.

A report

3.2.2.3 Future Development Requirements. Fiber op t ics i s a re la - t i ve ly new science with poten t ia l f o r obswvations i n 2r2;s

where access l imi ta t ions and/or obstructions prevent t h e use of morel conventional viewing equipment, a l i t e r a t u r e search in to nuclear applications of t h e technology. mental conditions expected t o preva i l a t t h e time of repair , and must be t e s t ed under actual, o r simulated conditions. Insulation, shielding, or cooling development may be necessary f o r scine of t h e equipment.

--

We recommend

All 3pt ica l equipment must meet t h e in -ce l l environ-

3.2.2.4 Cost Estimate. A quarter-manyear e f fo r t should be scheduled f o r t h e f i r s t phase of a maintenance development program t o invest igate op t i ca l viewing means and t o provide recommenda- t i ons and e,stimates for subsequent f e a s i b i l i t y t e s t i n g and mockup studies.

--

3 Closed Circuit Television - 3.2.3.1 Experience, Many advances have been made i n t e l ev i s ion

technology f o r nuclear applications during t h e past few years e General E lec t r i c Company, Westinghouse, and others rout inely use TV f o r in-service and spec ia l inspections of reactors . 1 2 7 1 3 9 1 4 a r e allso avai lable from i n -ce l l surveil lance and from hot c e l l users.L5916 ing reisctor repa i r and surveil lance of t h e HRT and MSRE reac t om. 1 7 9 1

-

Closed c i r c u i t TV performance evaluations

ORNL has a l so used te lev is ion f o r observ-

3.2.3.2 Future Development Requirements. The TV camera and wiring must b e able t o withstand t h e in -ce l l temperature and radia- t i o n f i e l d . Insulation, shielding, or cooling system development may be necessary.

10

3.2.3.3 Cost Estimate. It i s recommended tha t a quarter manyear e f fo r t and $10,000 equipment money be provided f o r Phase I of a maintenance development program t o procure rad ia t ion and temperature r e s i s t an t TV equipment, and t o update design c r i t e r i a , performance specif icat ions and cost estimates f o r subsequent development work.

3.2.4 Special Inspections

3.2.4.1 Experience and Future Development Requirements. Refer t o the report by R. W. McClung, Remote Inspection of Welded Joints , ORPJL-TM-3561, September 1971.

3.3 In-Cell Handling Tools

3.3.1 Li f t ing Devices

3.3.1.1 Concept and Experience. Oak Ridge National Laboratory's standard practive has been to build cradle-type l i f t i n g devices f o r a l l reactor system components a t t he time of t he components' i n i t i a l i n s t a l l a t i o n i n t h e c e l l ; and t h i s has grea t ly simplified the subsequent remote handling. 6'19 It i s necessary, however, to bu i ld t h e f ix tu re s with features t h a t f a c i l i t a t e t he use of remote "slip-on" guides or hook- i n se r t r ings f o r handling. Experience has shown a l so t h a t where possible, programs f o r crane movements should be for - mulated and documented while t he plant i s being b u i l t .

3.3.1.2 Future Development Requirements. All i n -ce l l handling too l s and l i f t i n g f ix tu re s a re usual ly of all-metal construction of materials compatible with the Hastelloy N primary system material, and of simple designs employing mechanical linkages. The too l s and f ix tures , therefore, have l i t t l e or no dependence upon in -ce l l environmental conditions during maintenance periods, with t h e exception of metal expansion when exposed to t he elevated temperature i n t h e c e l l . L i t t l e time and e f fo r t w i l l be required t o adapt tools of e a r l i e r designs f o r fu ture applications. Specific f ix tu re s and tools, however, must be proof tes ted , and operating procedures must be established and documented e i the r during t h e construction of t he reactor, or i n f i l l - s c a l e mockup t e s t s .

3.3.1.3 Cost Estimates. An engineering e f fo r t of about 1 1/2 manyears f o r design and development of handling too l s w i l l be required, plus $20,000 f o r materials and prototype equipment.

3.3.2 Miscellaneous Long-Handled Tools

3.3.2.1 Concept and Experience. Tools i n t h i s category include simple, long-handled u t i l i t y hooks and rods f o r i n -ce l l uses t o i n s t a l l , o r remove, insulation, heaters, e tc . The

11

too ls a re aI.so used t o a s s i s t pickup and t r ans fe r operations; typical. too;. desi ns and operations are documented fo r HRT repa i r work. 6,20,%

3.3.2.2 Future Development Required. None specif ical ly; t o o l s w i l l be developed along with the components they w i l l serve.

3.3.3 Portable Retaining Brackets

3.3.3.1

3.3.3.2

Concept and Experience. Reactor c e l l roof blocks and c e l l s ides shoulc! contain hooks and shelves upon which t o hang o r s e t porta’ble brackets f o r the temporary parking of m i s - cellaneous m a l l i n -ce l l items, such a s insulat ion jackets, heaters, etc. , and repa i r tools . Portable brackets resembl- ing cases fc:r milk b o t t l e s were used for HRT and MSRE c e l l work.

Future Development Required. None specif ical ly; brackets w i l l be developed along with t h e components they w i l l support.

3.3.4 Thermocouple and E lec t r i ca l Connector Tools

3.3.4.1

3.3.4.2

3.4.1.1

Concept and Experience. Simple, long- handled, s c i s sor- act ion too l s were designed for HRE and MSRE in-ce l l thermocouple maintensnce. The base of t he thermocouple t o o l accommodates the male and female halves of a couple. The too l ’ s actuator i s used t o open or close the scissor linkage t o e i ther make or break t h e coupling. Similar t oo l s a r e a l so available fo r push-pull type e l e c t r i c a l connector assembly and disassembly. Wrenches w i t t i long handles are avai lable f o r use with multiple- pin connectors for instruments and controls. The wrench i s used t o engai:e and tu rn t h e connector’s screw coupling. A sc i ssor motim actuator, b u i l t i n to the wrench tool , i s em- ployed -LO alj-gn and make o r break the coupling halves. Thermo- couple tools, e l e c t r i c a l connector t o o l s and other ORNL handl - ing equipment items a re described i n t h e ORNL Remote Main- t enance Cat a:l.ogue.

Future Development Required. None, except f o r mater ia l sub- s t i t u t ions .

3.4 -- Tool and Equipment Conveyance Means

Concept and Experience. It i s assumed tha t t h e portable shield maintenance technology developed f o r t he HRE and t h e MSRE w i l l be applied with molten s a l t breeder reactors.” Cel l conditions w i l l determine t h e need f o r a i r locks, e tc . , however, t h e basic scheme, proven i n pr ior operation of t he experimental reactors, w i l l be t o u t i l i z e portable shields of lead or s t e e l and t o arrange t h i s metal l ic shielding t o protect t h e operator from radiat ion a f t e r access holes have been opened on top of t he c e l l blocks. The portable shield

12

w i l l a l so provide t h e operator with a shielded platform f o r loading too ls i n to t h e ce l l . Loading holes w i l l be located within a c i rcu lar turntable in se r t within t h e portable shield platform t o permit t h e too l s and/or f ix tures t o be located and centered over t h e work area as required. of t h e shield will a l so include hooks and bars t o provide temporary hanger supports f o r maintenance too ls and mobile equipment o r components items. The platform of t h e portable shield w i l l again a l so be comprised of two separate sections t o allow t o t a l access f o r t he t r ans fe r of la rge equipment items in to t h e c e l l through the portable sh ie ld ' s platform frame opening. The reactor building would be temporarily evacuated f o r t h i s type of maintenance operation. The t rans- f e r s of large equipment items e n t a i l closed c i r c u i t TV opera- t ions and a zinc-bromide viewing window from a d is tan t spe- c i a l l y shielded control room.

The underside

3.4.1.2 Future Development Required. The portable maintenance shield approach must be incorporated in to the o r ig ina l c e l l and c e l l roof block layout design. Mockup t r i a l s w i l l be required t o es tab l i sh operating instruct ions and guides f o r maintenance. Costs f o r t h i s e f fo r t a re undetermined at present.

3.5 Pipe Cutting Equipment

3.5.1 Pipe Cutters

3.5.1.1 Experience. totype un i t s of t h e automated, o r b i t a l pipe cu t t ing and welding machinery as par t of a f e a s i b i l i t y study f o r t h e MSR maintenance program. 2 3 able t o cut pipe, t r i m t he ends square, and prepare end bevels on schedule 40 s t a in l e s s s t e e l pipes i n s izes up t o 6 inches i n diameter with r e l a t ive ly l i t t l e d i f f i cu l ty . However, problems arose i n cu t t ing Inconel because of i t s work-hardening tendencies, and more d i f f i c u l t i e s a re expected f o r work on pipe s izes la rger than 6 in. as t he cu t t ing operations were slow, cu t t e r feed r a t e s were minimal, and cu t t e r s dulled rapidly and required frequent replacement.

In 1968 and 1969 ORNL developed and t e s t ed pro-

The machining head (see Fig. 2 ) was

A l l ORNL machining t e s t s were performed on horizontal Figure 3 i l l u s t r a t e s a cu t t ing operation on 6 in.

S l i t t i n g saws and double bevel cu t t e r s tracked t r u e piping. pipe. within approximately 0.003 in. Single bevel cu t t e r s tend t o walk out of, and away from t h e cut, especial ly on t h e harder Inconel pipe. capabi l i t i es appeared adequate. Observations indicated, however, t ha t the carriage drive i s the l imi t ing fac tor on cu t t ing cap- ab i l i t y . We observed r o l l e r slippage on the pipe and frequently t r ipped the carriage drive r o l l e r c i r c u i t breaker protection. Cutter feed and carr iage t r a v e l speed adjustment changes, how-

withstood loading and vibrations caused by t h e mil l ing cut ters ,

The cu t t e r drive motor power and speed control

ever, restored operations. The carr iage and machining head -

.

Fig. 2. O W L Cutter or Machi

14

Fig. 3. ORNL Orbital Cutting Equipnent

W but only with proper t r a v e l speed and t o o l feed select ion. Improvements;, however, a r e required to provide a stronger and more pos i t ive cu t t e r depth control and to provide more s t ab le longitu.dina1. adjustments. A spl i t -bear ing sleeve carr iage concept development i s proposed (see 2.5.1.2) which could provide means for a more r i g i d cu t t ing assembly which could s t i l l be remotely i n s t a l l e d and operated f o r i n - c e l l pipe cu t t ing needs. Otherwise, improved locking clamps a re desired i n con- junct icn w i t h t h e present carr iage for prevention of long- i t u d i n a l an6 r a d i a l cu t t e r s h i f t s . Pipe co l l a r clamps a r e required f o r pipe cu t t ing operations where t h e pipe slopes i n excess of 5 degrees from horizontal.

We have cut with high-speed and Circoloy a l loy s l i t t i n g saws and mi l l ing cu t te rs . The alloyed tool s t e e l appeared t o s t ay sharper longer, - possibly by as much as a f ac to r of one and a h a l f . Tests with carbide cu t t e r blades showed an even longer blade l i f e . Carbide too ls , however, a r e b r i t t l e , and we d i d break some blades, probably a s a r e s u l t of blade chat ter . Ef f ic ien t cu t t ing requires t h e th ickes t possible chip per cu t t i ng toot:n, but t h i s may have to be compromised considerably t o obtain reasonable cu t t e r l i f e and proper surface f in i sh . Thi,; i s pa r t i cu la r ly t r u e i n t h e case of high- n icke l stee1,s where t h e base mater ia l tends to work-harden with t h e r e s u l t t h a t chip removal. i s inadequate or incom- p le te . Resu:Lts from Inconel machining experiments ind ica te t h a t t h e cu t t i ng edges of a l l cu t t e r t e e t h must be generously relieved t o 19rovide ample clearance f o r ch ip fa i loEt . Allow- ing chips t o f a l l out f r e e l y w i l l . minimize t h e Inconel work hardening caused by trapped chips. It i s a l so qui te important t h a t a l l t e e t h of a cu t t e r engage t h e work during cut t ing, Off-the-shelf commercial cu t t e r s used appeared t o cut with usua l ly only about a four th of t h e i r t ee th , and imprcved cu t t ing w a s noted where cu t t e r s were reground l c c a l l y t o p r e c i s i m specif icat ion. be at ta ined.

Almost 75% tooth engagement can

The impwtance of proper t o o l t r a v e l and c u t t e r speed adjustments, espec ia l ly f o r cu t t i ng Inconel materials, cannot be minimized. Available machine shop machining data do not app.Ly t o t h e o r b i t a l cu t t ing assembly because our equipment does not; have t h e dr iving power of shop machines. Aiso, dry macliining i s spec i f ied for nuclear r-Zc.2; i ; r syztem 1" I -

tenance because coolants a re e i t h e r hazardous or might con- taminate t h e nuclear system. Therefore t h e tool t r ave l , cu t t i ng speeds, and t o o l feed r a t e s must be severa l magni- tudes lower than usual shop pract ice .

Table I shows t h e number of inches of cut a blade can be expected to make before it must be resharpened. a l so shows how deep t h e blade would cut i n t r ave l ing t h e indicated numbm of inches around a 6-in.-diam pipe, taking a 30 m i l or a l.2 m i l cut, a s indicated.

The t a b l e

Table 1. Expected Life of Cutter Blades ~~

Des c r i p t ion Blade Lifetime

In S ta in less S t e e l In Inconel ~ ~~~~ ~~~

Saw Tooth Speed 70 t o 80 ft /min 50 ft /min Carriage Speed 3 1/4 in./min 1 in./min Feed Per Tooth .001 i n . .0005 i n .

Inches of Total Depth Inches of Total Depth cut, average of cut, 6-inch cut, average of cut,

6- inch

inches.

depth 30 mils. pipe wall . depth 12 mils. inches inches inches pipe wall .

1/16-in. - th ick s l i t t i n g saw, 3 in . dia . , 32 t e e t h high speed s teel 530 3/ 4

1/16-in. - th ick s l i t t i n g saw, 3 in . d ia . , 32 t e e t h Circoloy a l l o p

3/32-in. - th ick s l i t t i n g saw, 3 in . d ia . , 32 t e e t h high speed s t e e l

3/32-in. - th ick s l i t t i n g saw, 3 in . dia . , 32 t e e t h Circoloy a l l o p

800 1 1/8 730 7/16

430 5/8

650 7/ 8 600 11/32

70" included double angle m i l l 2 3/4 in . d ia . , 20 t e e t h , 1/2 in . wide high-speed s tee l 470 11/16 420 1/4

P n

*Trade name for Circular Tool Company (Providence, R. I. ) spec ia l high-speed s t e e l a l loyed blades of high carbon, medium chrome, high vanadium, high tungsten and medium cobal t composition.

17

WE? selected cu t t ing speeds between 70 and 80 surface fpm for cut t ing s t a in l e s s s t e e l materials, and chose 50 fpm for Inconel i n order t o achieve reasonable cu t t e r l i f e . These c:utting speeds correspond t o approximately 100 and 62.5 revolut;ions/min f o r t he 3-in. -diam a l loy s t e e l s l i t t i n g saws. Feed per tooth selections compatible with t o o l strength and t o o l r i g i d i t y were 0.001 in. for s t a in l e s s s t e e l work and 0.005 in. for Inconel with 3 1/4 and 1 in./min ( t ravers ing surface) blade t r a v e l ra tes . Our feed per tooth r a t e s a re low when conipared t o r a t e s i n standard machine shop work, but a r e s t i l l credi table considering our small-sized and low-powered e uipment. Our cu t t e r motor consis ts essen- t i a l l y of a 1 3 7 hp e l e c t r i c d r i l l . The depths of cut depend on avai lable hp and cu t t e r shapes, and on the sharpness of t h e cut ters , as they i n tu rn a f fec t t h e power required a t t h e cu t te r motor spindle. We repeatedly cut 0.030 in. deep in to s t a in l e s s s tee l , and 0.015 in. i n to Inconel.

A l l of our machining operations with the ORNL o r b i t a l equipment must be accomplished i n the standard "milling up'' mode of operation where the cu t te r tooth i n contact with the pipe i s moving i n the same direct ion as t he carriage. lack r ig id i t ,y f o r reverse, o r "climb m i l l " cutt ing. Our carr iage 's to rs ion bar clamping act ion on the carriage r o l l e r does not give enough f r i c t i o n contact f o r climb cutting.

We

Oak Rid.ge National Laboratory a l so has experience with t h e Trav-L-C'utter pipe saw and Guillotine pipe saws manufac- tured by t h e E. H. Wachs Company of Wheeling, I l l i n o i s , and with pipe cu t t ing and beveling machines of t h e H & M Pipe Beveling Machine Company of Tulsa, Oklahoma.

The Wachs equipment i s avai lable with a i r o r e l e c t r i c drives i n horsepower ra t ings equivalent t o machine shop saws. H & M equipment i s e l ec t r i ca l ly driven; t h e i r cut ters are furnished with e i the r pneumatic or e l e c t r i c a l drives.

One of t he prime objectives of t he Fast Flux Test Faci- l i t y (FFTF) a t Hanford i s t o perform nuclear fue l s t e s t i n g f o r t h e Liquid Metal Fast Breeder Reactor ( W B R ) program. The t e s t f a c i l i t y must have the capabi l i ty t o i n s t a l l and remove f i e 1 assemblies by remotely controlled equipment. A s izeable program i s underway a t t h e Hanford Engineering De- velopment Laboratory (HEDL) t o develop and t e s t equipment with which t o cut and weld the open- and closed-loop reactor top closures f o r removal and r e ins t a l l a t ion of experimental t e s t assemblies. 2 4 welding, and re la ted equipment f o r appl icat ion t o r e l a t ive ly small (6.72-in. mean diameter) pipe. They a re t e s t i n g t h e i r equipment i n a mock-up a t 500°F. Their material and equipment s e l e c t i m s are intended t o withstand lo5 R/hr gamma rad ia t ion exposures.

ORNL i s monitoring t h e i r development of cutt ing,

1%

3.5.1.2 Future Development Required. Cell layout and avai lable orb i t clearance around pipes f o r t h e sawing and beveling equipment w i l l be important fac tors i n determining the select ion of machinery f o r remote maintenance and repa i r operations. The ORNL equipment described i s compact and lightweight. Our carriage-cutter head working un i t i s designed t o be remotely clamped around a pipe and i s about 4 in. th ick i n r a d i a l dimension, and 10 1/2 in. long. The technology for i t s application t o cut and/or bevel pipes remotely by automated programmed controls i s established. Our compact equipment, however, i s l imited i n power f o r both t h e t o o l t r a v e l propulsion and the t o o l feed.

Subsequent sections of t h i s report and Appendix "B" discuss an a l t e rna te carriage design using a spl i t -bear ing sleeve. The spl i t -s leeve carr iage i s supported by a se t of spli t-bearings on each end. A separate motor gear drive, mounted t o the pipe, couples t o a spl i t -gear which i s permanently attached t o one of t he sleeve's end bearings and drives t h e sleeve around the pipe. This a l t e rna te design o f fe r s considerably more r i g i d and uniform carr iage propulsion than i s avai lable from the f lex ib le , horseshoe- shaped ORNL carriages. Rigid carriages a re desirable for pipe cut t ing service; cu t t e r t o o l vibrations, or t o o l chat ter a r e minimized, and cu t t e r s h i f t tendencies a re eliminated. A strong poss ib i l i t y ex is t s , however, t h a t pipe ends w i l l tend t o spring apart r ad ia l ly (and ax ia l ly ) when cut. The magnitude of t h i s s h i f t tendency w i l l be determined by ac tua l process system layout and piping supports. i n t he la rger pipe s izes . We, therefore, an t ic ipa te t h a t t he spl i t -bear ing sleeve carriage design may be l imited t o cut- t i n g applications on t h e smaller pipe s izes , say, up t o through 6- or %-inch pipes. Beyond these s izes strong pos- s i b i l i t i e s preva i l t ha t sleeve end bearings cannot withstand t h e forces resu l t ing from t h e spring-action when t h e pipe i s cut, and the bearings may be deformed or crushed. These carriages would a l so require a minimum of 10 inches pipe clearance, as contrasted t o t h e 4-inch r a d i a l clearance re- quirement f o r basic ORNL carriages.

It w i l l be most pronounced with short pipe runs, and

Split-sleeve carriage r i g i d i t y of fe rs advantages f o r remotely operated pipe cu t t ing and pipe end beveling opera- t ions, plus the poss ib i l i t y of mounting and supporting cut- t e r s or brushes t o such carriages for i n t e rna l pipe cleaning needs. (See 2.9.1.2). Also, these carriages could probably be used f o r maintaining pipe alignment during pipe cu t t ing operations. (See Appendix "B" ). These poten t ia l benefi ts seem t o outweight t h e aforementioned disadvantages and suggest t h a t a development program would be j u s t i f i e d t o estab- l i s h f e a s i b i l i t y and l imitat ions.

c

19

The Wach's equipment has ample power, but t he equipment i s considerably la rger and heavier (by a fac tor of 10 plus) ; it requires substant ia l o rb i t clearance. The outside dimensions f o r a Wach's Trav-L-Cutter a r e 24 3 / 4 X 11 1 / 2 X 20 in. , as compared t o 9 X 4 X 10 1 / 2 in. f o r t h e ORNL o r b i t a l equipment. Guil:l.otin saws do not require o rb i t clearance. They usual ly f i t a space i n the order of 6 in. beyond each pipe side, with t h e i r operating mechanism i n a fixed plane extend- ing up t o 3 1/2 pipe diameters on one s ide f o r a width of about 6 inclies along the pipe. Guillotine saws can be u t i l - ized only t o sever o r s t ra ight cut pipes; they cannot make bevel cuts.

3.5.1.3 Cost Estimat;es. No work has been done t o adapt commercial -- sawing machj-nery f o r remote in s t a l l a t ion . design, development, fabr icat ion and checkout program i s estimated t o require about 1 3/4 manyears of e f fo r t plus about $24,000 f o r materials, fabr icat ion, t e s t samples, and mockups. The cost excludes prototype machinery acquis i t ion costs of about $3800 fo r a Trav-L-Cutter and about $1200 f o r a Guillotine saw with up t o %in. pipe sawing capacity.

An equipment

There Ere a number of manufacturers who market pipe cut t ing and beveling machines and la thes f o r pipe-end preparations. The machines a re normally used by pipe fabr i - cators and ksy large construction companies t o prebevel pipe ends f o r cocstruction welding. Typical machinery consis ts of c i rcu lar gear tracks, o r horseshoe-shaped gear tracks, t o be in s t a l l ed over pipes, with the t rack u t i l i z e d t o orb i t e i t he r a torch o r an end m i l l f o r cu t t ing and/or beveling. ORNL has ex-gerience i n using an H & M "Pipe-End-Prep Lathe" t rack t o handle 14 t o 20 in. pipes. po ten t i a l fo:r conversion t o remote operation. It i s defini- t e l y adequate f o r flame-cut and bevel preparations, but lacks a properly fimctioning precision "out-of-round" s l i d e attachment t o accurately monitor and gauge t h e out of roundness prevail ing i n commercial pipes so t h a t compensating t o o l posi t ion changes can be made. type equipment of fe rs ce r t a in merits f o r consideration. Equipme.nt dimensions, weight, and o rb i t clearances a re i n between t h e dimensions l i s t e d f o r ORNL and Wachs' equipment. If the H & M equipment i s t o be used f o r reactor work, individual t racks should be selected fo r each pipe size. The frame-tracks f o r multiple pipe s i ze application lack some r ig id i ty , and may o f fe r too large an envelope when used on the sma:L1 end of t h e i r pipe capacity range. It i s estimated tha t , if performed i n conjunction with the previously proposed work f o r developing remotely operated saws, t he development of a wo:rkable H & M t rack t o handle a representative 12 in. ]?ipe cut and bevel preparation would require 3/4 manyear and $85C10. would be i n -:he order of $2500.

H & M equipment has

The wri ter believes tha t H & M

Additional costs f o r H & M equipment items

20

A note of caution i s repeated: labor, material, and machinery costs quoted previously a re based on standard cu t t ing pract ice with environmental temperature service l imited t o possibly as high as 300"F, and radiat ion leve ls up t o about l o 4 R / h r . It may be necessary t o develop sub- s t i t u t e materials t o meet t he contemplated high-temperature and high-radiation service requirements. development and f o r subs t i tu te materials of construction w i l l be additive. t h e l imi t ing c e l l conditions so as t o determine t h e addition- a l research and development needs.

A l l costs f o r such

A study should be performed f i r s t t o determine

3.5.2 Seal Weld Cutters

3.5.2.1

3.5.2.2

Experience. including Diaphragm and Seal P la te Weld schemes, Fig. 4; Sandwich Seal Weld schemes, Fig. 5 ; Canopy Weld schemes, Fig. 6; and Seal Lip Closures, Fig. 7. The welded sea ls shown i n the i l l u s t r a t i o n s a re types f o r which standard cut- t i n g equipment can be adapted t o work by remote control. More detai led discussions a re given i n Section 2.14.4, "Seal Weld Closure Welding. "

There a re a number of schemes f o r s e a l welding,

Various mil l ing and/or grinding means a re normally used with conventional hand tool ing t o sever t h e seals . To t h e best of t he wr i te r ' s knowledge, with t h e exception of mounting portable grinders t o extension handles t o loca te t h e t o o l operator away from any d i rec t radiat ion beams, and/or t o permit t h e i n s t a l l a t i o n of portable lead shielding between the work and the operator, Oak Ridge National Labora- tory, t o date, has had no experience i n t o t a l l y remote cu t t ing of s e a l welds.

Future Development Required. Specific tool , t o o l support, and t o o l manipulation devices w i l l vary for each of t h e types of s ea l weld l i s t e d . Oak Ridge National Laboratory has assembled a f i l e of s e a l weld cu t t e r too l ing select ions based on published maintenance information and on observa- t ions of naval shipboard practices. The f i l e includes information on grinders and grinding wheels, pipe cu t t e r s and cu t t e r b i t s , saws and blades, pipe-end prep machines and tools , pipe centering and pipe expansion devices.

No time or cost estimate can be prepared pr ior t o select ing the s e a l jo in t or j o in t designs. The development e f fo r t f o r t he jo in t cu t t e r should be performed i n conjunction with reweld machinery t r i a l s . It i s recommended tha t t h e designers se lec t t en t a t ive sea l weld con- f igurat ions now and thereby permit t he developer t o proceed with a f e a s i b i l i t y study t h a t could include too l ing design, purchase, adaption, and t e s t s . Test r e su l t s should influence and provide direct ion t o t h e f i n a l MSBR sea l design.

W

21

ORNL DWG 73-2389

Fig. 4. Seal P l a t e Welds

22

23

ORPJL DWG 73-2391

,,'

Fig. 6. Canopy Weld Schemes

24

SPhC\hL

ORNL DWG 73-2392

+ .--

I

Fig. 7. Seal Lip Closures

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3.5.2.3

3.6.1.1

3.6.1.2

Cost Estimates. It i s estimated tha t a budget of th ree manyears zG$c;0,000 could es tab l i sh worthwhile gui?!,l f ~ 3 s for preliminary seal-cut and seal-reweld f e a s i b i l i t y evaluation. (Note: Item 2.14.2, "Closure Welding - Seal Welds" development costs a re included with t h i s estimate. )

The cost estimate caution l i s t i n g s ta ted previously a l so appl i e s her e.

3.6 EauiDment f o r PiDe SDreading

Concept; and Limited Experience. After cut t ing the pipes on each s i d e of a component one must spread them apart t o permit t h e i-eady removal of t he component. Depending on loop layout:, it may a lso be necessary t o jack up one o r t h e other of the pipe ends adjacent t o t he cut t o eliminate binding f o r t h e remainder of a cut. For remote operational needs it i s planned t o u t i l i z e t h e special pipe alignment machinery discussed i n Section 2.12, "Pipe Aligning Technology" t o a l so serve the pi-pe spreading needs, a t l e a s t f o r t he smaller pipe s izes .

WE! have l imited experience i n resolving pipe res t ra in- ing problems associated with pipe s l i t t i n g operation. Spl i t - saw c u t t e r hench t e s t s showed t h e importance of select ing the proper pipe support locat ion r e l a t i v e t o t h e orbi t ing p la t - form. Care must be taken t o permit f r e e movement of t h e cut piece, and t;o prevent t h e binding of t h i s piece against t he saw. Slit-saw cu t t e r materials a re b r i t t l e ; our t e s t t r i a l s showed tha t it i s possible t o crack and break a res t ra ined saw blade.

Future - Development Required. Refer t o item 2.12, "Pipe Aligning Technology".

3.7 Carriers a.nd Convevance Means f o r Use Within the Cell

3.7.1.1

3.7.1.2

3.8.1.1

3.8.1.2

Experience. Carrier technology from ORNL and other in- s t a l l a t i o n s i s avai lable so t h a t spec ia l i s t s i n ca r r i e r de- s ign can meet whatever requirements a re established by the f i n a l des igrl of system component s . Future Development Required. None anticipated.

3.8 Carriers f o r Use Outside t h e Cell

Experience. a t ions i s avai lable so t h a t spec ia l i s t s i n ca r r i e r design can meet whatever requirements a re encountered.

Carrier technology from ORNL and other i n s t a l l -

Future - Devehpment Required. None anticipated.

3.9 In-Cell Preparations for Equipment Reinstallation

3.9.1.1 Definitions and Experience. Final preweld pipe-end joint preparations include kerf and/or chip removal from the open pipe joint, removal of salt including salt traces clinging to the pipe wall and the installation of a suitable purge block plug into the pipe near the open joint. establish acceptable environmental, off-gas airlock and ventilation conditions for the cell. A l l cutting chips from mechanical sawing, kerf from plasma flame cutting, and salt residue on interior pipe walls adjacent to the cut joint, must be totally removed from the pipe prior to in- stalling purge blocks or making a facsimilie in preparation for final pipe rewelding. Provisions must be made and incorporated with air locks and ventilation systems, t o permit the cell off-gas system to safely handle purge and welding gases from subsequent pipe rewelding operations. ORNL has had considerable experience for some of the categories from operational maintenance experiences with homogeneous reactors and the MSRE. 5’6’23 Additional information is also available from the remote top closure evaluation work of the FFTF at Hanford, Washington.

One must also

24

3.9.1.2 Future Development Required. in a reactor project and should combine the efforts of the reactor designers and maintenance personnel to assure that the piping system layout provides adequate clearances for maintenance equipment and for the introduction of replacement components. The group should discuss all phases of the repair and reinstallation requirements. Special tools and other requirements that become apparent from the discussions (such as a pipe wall scraper for removing traces of salt from pipe interior) should be listed and categorized. Where possible, new tooling requirements should be combined with existing tooling, or at least with the masts and manipulators of existing long-handled tools.

A study should be started early

3.9.1.3 Cost Estimates. It is estimated that 1 1/4 manyears and $18,000 will be required to perform the supplemental work, including the cleanliness control work discussed in Section 2.10 below.

3.10.1.1

3.10 In-Cell Cleanliness Control

Definitions and Experience. cludes all the precautionary measures t o assure that all prewelding cleanliness requirements of the ASME Code and RDT Standards are met and maintained throughout the welding operation. Wiping joints with acetone solvent and lint- free rags before welding, proper filing of defects observed between passes, and brushing of all weld bea.ds, etc. are terms of cleanliness control that have been found t o be necessary.

In-cell cleanliness control in-

259 269 27

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3.10.1.2 Future Devel.opment Required. Cleanliness control development requirements and associated costs a re included with the l i s t - ing of item 2.9 above.

3.11 Conveyance - of Components t o Reinstal la t ion Location

3.11.1.1 Experience. Carrier and conveyance technology can be ob- - ta ined from ORNL and other i n s t a l l a t ions fo r d i rec t applica- t i o n t c remote maintenance problems.

3.11.1.2 Future - Development Required. None anticipated.

3.12 Pipe Alignment Technology

3.12.1.1 Concept and Experience. There i s only l imited p rac t i ca l - experience with t h e use of remote control equipment t o spread t h e ends of pipe a f t e r cutting, t o posi t ion new components i n proper alignment, and t o hold them i n posi t ion during welding. Most of t h e avai lable reactor maintenance experience docu- mentation r e fe r s t o underwater maintenance, with e i the r t he c e l l o r t he (component p a r t i a l l y flooded. Molten Sal t Breeder Reactor (MSER) maintenance must be performed under dry conti- t ions . The l imited dry experience t h a t i s avai lable i s pri- marily from work i n t he MSRE mockup and i n the MSRE c e l l where special ly mounted screw-jacks were in s t a l l ed i n conjunction with freeze flanges i n the primary pipe system t o spread o r close the flanges. Instructions f o r pipe alignment were developed as a par t of t he extensive Westinghouse Pennsylvania Power and Light Company study f o r t h e Pennsyl- vania Advanced Reactor Program (PAR)28 of t he l a t e 1950's. The PAR was planned t o use a c i rcu la t ing aqueous s lur ry f u e l pressurized l;o 1000 psi . The designers recognized tha t a c i rcu la t ing fue l would increase the radiat ion leve ls i n t h e reactor system areas and t h a t completely remote maintenance w o u l d be mandatory. The remote control devices and procedures planned f o r use on t h e PAR system are described i n the fol.lowing paragraphs.

The primary coolant systems of t h e PAR consisted of closed :Loops, each with but one point fixed. Hence, posi- t ioners to rea l ign t h e pipe f o r welding were not required t o apply bending moments t o t h e piping and only simple radi- a l and a x i a l motions were needed t o g r ip t h e pipe and t o a l ign t h e pipe ends. e r thermal cycles which would introduce s t resses t h a t would cause t h e pipe ends t o spring from t h e i r o r ig ina l posi t ion when t h e pipe was cut. The PAR design c r i t e r i a regulated primary pipe s t r e s ses t o l i m i t pipe expansions so tha t no point of t he piping would move i n excess of 1/2 inch during t h e f lexure from hot t o cold posit ion. because of i t s weight and hanger design, had the completely fixed posit ion. A l l other components and the piping were

PAR loop piping was expected t o encount-

Their reactor vessel ,

28

f ree t o move about t he reactor i n a horizontal plane. Be- cause of t h i s f l e x i b i l i t y , only r e l a t ive ly simple posit ioner devices were required t o properly hold piping f o r severance operations and t o rea l ign t h e replacement piping p r io r t o welding. cut points included jaws t o firmly g r i p t h e pipe. t i n g and welding equipment could move r ad ia l ly and ax ia l ly f o r realignment and mounting. Cut points were preselected on horizontal pipe runs t o fur ther reduce bending moment requirements for t he replacement piping. system (16-in. pipe) posit ioner design assumed that the maximum loads t o be imposed on the pipe, i n e i the r t h e r a d i a l or t he a x i a l direction, would be 15 tons and tha t a 1-in. ax i a l movement of t he pipe t o provide clearance would be adequate f o r removal of t he components. Replacement components contained nozzle configurations iden t i ca l with t h e removed component. Crane access was chosen t o posi t ion new components within 1 in. of t he f i n a l i n -ce l l location. A l l ax i a l and r a d i a l loads were transmitted t o permanently in s t a l l ed struc- tures . These supports were designed not t o def lect under the calculated loads required for pipe manipulations. During t h e removal of a component, i den t i ca l posi t ioners would be lowered over t he piping onto t h e r i g i d s t e e l s t ructures on each s ide of t he cut point. supports, t h e i r self-contained hydraulic systems were t o provide a l l t he forces required t o r e s t r a i n or a l ign the piping. Final alignment was t o be accomplished t o within 1/32 in.

Narrow clamping band un i t s on each side of t he The cut-

The PAR primary

After t he posit ioners were locked t o t h e

The termination of t he PAR project precluded complete t e s t i n g of t he maintenance schemes t o show tha t they would accomplish a l l t he res t ra in ing and pipe aligning manipula- t i ons required f o r proper cu t t ing and rewelding work setups. The project, however, d i d conduct equipment t e s t s t o es tab l i sh remote maintenance f e a s i b i l i t y and t o provide valuable guidelines fo r fur ther studies.

Among t h e problems t h a t remained when the PAR work had discontinued was the f a c t t h a t t he maintenance equipment and the posit ioning equipment components were bulky and complex. numerous pipe sizes, and each demanded a great deal of c e l l room. Although O m ' s approach t o posit ioning w i l l generally follow PAR guidelines, we plan t o use grea t ly simplified apparatus. For example, piping w i l l generally be cut a t component stub nozzles. The posit ioner support therefore can be incorporated t o the component's s t ruc ture or framing a t considerable space savings. Pipe def lect ion movements can be minimized. Figure 8 exemplifies a possible arrangement.

Many posit ioners were required t o handle the

29

ORNL DWG 73-2393

Fig. 4. Component Pipe Stub Weld Jo in t Pos i t ioner Arrangement

Fig. 9. Pipe Alignment J i g f o r Line Cutting and Welding

30

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Component ( A ) and typ ica l connecting pipes ( B ) and (c ) a re commonly supported by framing ( D ) area (E) has accurately machined ( t o be t t e r than normal m i l l dimensional tolerances ) piping, precision indexed t o component reference l ines . A permanent pipe clamping f i x t u r e (F) i s both adjustable and removable. The f i x t u r e includes a centered r ing groove t o accomodate a r ing welded t o t h e pipe. The in tegra l pipe r ing permits t he f i x t u r e t o s h i f t ax i a l ly during loop heatup expansion and cooldown contraction to minimize t h e introduction of bending moments and s t resses t o the pipe. contain a n t i g a l l spray coatings. ment operation i s presently envisioned as follows:

Preselected cut-point

The mating surfaces of t h e pipe clamp f ix tu re w i l l A t yp ica l component replace-

1. Mount t h e "orb i ta l vehicle" carr iage over area ( E ) .

Apply module's inspection gear t o pro- Inser t an inspection module. cured over pipe (B) . perly index the carriage a t t h e preselected cut-plane; lock carriage drive t o pipe.

Verify t h a t clamp (F) i s se-

2. I n s t a l l a catch pan and a vacuum cleaner system f o r "hot chip" control. I n s t a l l a cu t t e r module i n exchange f o r t h e inspection module. Test indexing - proceed t o cut.

Transfer equipment t o pipe l i n e ( C ) ; repeat opera- 3. t ions 1 and 2.

4. Detach component (A) from i t s support, a t tach a l i f t i n g f ix ture . Use crane for removal.

5. Enter replacement component (A' ). I t s pipe stub has been previously machined t o template indexing data. Component ( A ' ) i s bagged, except for stub pipe weld ends, and lowered i n place. Bo l t component (A' ) t o supports. Attempt t o match stubs and piping. If stub ends a re too long, matchmark pipe, remove component, remachine. If stubs a re too short, obtain wax impressions for machining a spool piece inser t . F i t as required t o a t t a i n jo in t alighment. Adjust t he permanent pipe clamp f i x t u r e (F) i f required, but only f o r small displacements t o avoid excessive s t ra ins .

We plan t o use special custom-built spool i n s e r t s t o connect pipes f o r rewelding i n places where it i s otherwise impossible t o a t t a i n sa t i s fac tory pipe-end alignment f o r rewelding. Many components contain multiple pipe connections. Depending on t h e respective azimuth locat ions of t h e pipe stubs on the replacement component, equipment maintenance procedures t o be developed i n t h e mockup w i l l more than l i k e l y require spool piece connectors fo r t h e makeup of some of these l ines . The spool piece scheme avoids t h e prestressing of pipes f o r f i t u p on the f i n a l l i n e attach- ments of multiple l ines . 1

31

6. Rei-nstall "o rb i t a l vehicle" carriage with the inspection module in se r t over pipe (B). ment of t he pipes and al ign the carriage. Clamp and lock carr iage drive t o pipe. Swap t o cu t te r module, m i l l t he adjoinfng pi.pe ends t o get t he precision needed. Remove the cu t t e r module, clean the prepared jo in t ; then i n s t a l l t h e weld module. Tack or stagger weld matched pipe ends t o avoid d is tor t ion . Perform similar work on pipe l i n e ( C ) . Finally, f in.ish weld both jo in ts .

Check the f i n a l align-

7. Remove repa i r equipment. Adjust t he supports and t igh ten bol ts . Whenever a pipe section or component i s removed a f t e r having been i n service, res idua l s t resses can ex i s t j.n t he piping and w i l l appear as forces and moments upon cut t ing t h e pipe. The forces and moments w i l l be present even though the piping may have been in s t a l l ed i n i t i a l l y i n a s t ress - f ree condition. Stresses can be caused by d i f - ferences between the ambient temperature a t which t h e piping was in s t a l l ed and t h a t which ex i s t s during maintenance opera- t ion, k~y thermal cycling i n system operation, by changes due t o yielding a t high-temperature operation (creep), or by changes of configureation caused by welding, or by sh i f t i ng of pipe support hangers, supports, o r s t ructures . The suggested scheme f o r cu t t ing only i n the v i c in i ty of t he component nozzle stubs and f o r using common-component pipe r e s t r a i n t clamp supports locates pipe cut points adjacent t o r i g i d components and tends t o reduce r a d i a l pipe movements and pipe bending moments. The scheme thereby minimizes problems with replacement components. The scheme a lso compen- sa tes f o r a x i a l pipe s h i f t s by l e t t i n g the pipe clamp f ix tu re s h i f t f r ee ly with the pipe's axis. culated maximum pipe s h i f t s t o be ant ic ipated i n cu t t ing of pipe i n a maintenance operation on a typ ica l r igh t angle bend pipe-line in s t a l l a t ion . The i l l u s t r a t i o n s selected represent "ideal" balanced symmetrical layouts; i n pract ice piping systems w i l l more than l i k e l y be f a r more complex. The de- f l e c t i o n and res tora t ion force figures, however, i l l u s t r a t e t h e magnitude of t h e problem, and t h e problems dependence upon pipe s i ze and lengths of pipe runs. The longer t h e pipe 's length, t h e greater i t s deflection, or shrinkage upon cut t ing, - but t he res tora t ion force requirements decrease with increased pipe lengths t o reduce the overa l l problem of jockeying pipes about t o a l ign an old in-ce l l pipe end with t h e pipe stub of a newly in s t a l l ed component. Smaller diameter pipes a re l e s s r igid, hence considerably l e s s force i s required to move t h e smaller l i n e s within the ce l l . Accordingly, t h e idea l c e l l pipe layout,from a maintenance standpoint, consis ts of long runs of small diameter balanced geometry pipe l ines . We a lso note negl igible angular pipe deflections f o r t h e proposed pipe supports affixed t o a common base with t h e respective components; t h e magnitude of t h e angular deflection, or rotat ion, upon cu t t ing the pipes i s not suf f ic ien t t o cause problems of matchup f o r butted ends for re-welding i f the pipe ends a re squared t o usual tolerances.

Appendix A l i s t s cal-

32

Reactor designers cannot predict a l l possible trouble areas, or it may not be p rac t i ca l t o provide pipe stub posi- t ioners a t every location where they might be needed. There- fore, a portable pipe alignment j i g f o r l i n e cu t t ing and welding, such as shown i n Fig. 9, w i l l be needed t o provide f o r pipe maintenance anywhere within t h e system. supported posit ioner assembly could swing in to place over t h e pipe t o be cut. Then, two hydraulic cylinders, housed with- i n the j i g ' s top cover, would be energized t o extend a s e t of contoured shoes t o firmly g r ip t h e pipe and press it in to the alignment j i g and rees tab l i sh r a d i a l alignment. Matching corner-cable s l ings a re i n tension to balance the applied hold-down forces, Narrow clamps designed t o g r ip the pipe firmly should be in s t a l l ed butted up to each s ide of t he j i g ' s shoes to minimize pipe bending moment s t resses when t h e pipe i s cut.

The cable-

3.12.1.2 Future Development Requirements. We should es tab l i sh which vessels a re t o be replaced, which ones to be repaired i n place, and which components of vessels a re t o be removed f o r repa i r or replacement. Expected pipe f l e x i b i l i t y needs should be estimated f o r comparison, and f o r t h e vessels t ha t a re t o be replaced it must be determined how pipe s izes , wall thick- ness, length and method of attachment t o t he vesse l w i l l influence t h e f l e x i b i l i t y . such as t h a t proposed f o r t h e MSBR's*' does not permit much f l e x i b i l i t y and it may therefore become necessary t o resor t t o t he use of t a i lo red spool pieces f o r short l a rge diameter pipe runs. Where the la rge coolant s a l t piping could have long runs, there may be enough f l e x i b i l i t y avai lable t o permit some maintenance pipe alignment, however, even : e r e pipe i n t h e 20 inch pipe range i s not ea s i ly bent. The smaller service l i n e s (6 and 8 inches diameter) could be made f l ex ib l e enough t o permit r e l a t ive ly easy alignment a f t e r t he vessel i s i n s t a l l ed and t h e la rger l i n e s welded together. The references t o t he PAR imply t h a t t h e la rges t vessel, or t h e reactor vessel, would be fixed and t h a t t h e other components would then be adjusted t o it f o r alignment. The ac tua l supports, rotat ions, and t i l t s of these "other components'' remain the major problems t o be resolved, along with the problems of properly holding the pipes for f i n a l alignment before welding. The designer-maintenance study group (see itme 2.9, "In-Cell Preparations f o r Equipment Reinstallation'! ) should analyze a l l i n -ce l l pipe systems for ant ic ipated pipe def lect ion s h i f t s and movements when t h e pipes a re severed during component replacement maintenance operations. Their analyses should determine t h e equipment and pipe support types needed, t he locations of t h e cut planes, and t h e space needed f o r pressure cylinder inser t ion t o move the pipe ends as required.

A t i g h t l y coupled arrangement

Alternatively, a study should be sponsored t o invest igate possible merits of u t i l i z i n g commercially avai lable s p l i t - bearing sleeves t o r e t a in pipe alignment f o r cu t t ing and to

33

reestal3lish alignment f o r preweld and weld-tacking assembly, as detai led i n Appendix B. There may be a pipe s i ze r e s t r i c - t i o n f o r an e f fec t ive range where spl i t -bear ing sleeves per- m i t a highly simplified approach t o pipe alignment maintenanse needs. An investigatory program should s t a r t ear ly i n t he reacto:r pro;ject. Sp l i t bearing sleeve maintenance, even i f pract icable only f o r t he smaller pipe sizes, would permit subs tan t ia l overa l l cost savings.

3.12.1.3 Cost Estimates. A f e a s i b i l i t y study on a selected small pipe s i ze of 3-in. sched 40 s t a in l e s s s t e e l pipe, o r of 3-in. 40 1ncone:L pipe, f o r spl i t -bear ing sleeve maintenance would en- t a i l about 3/4 manyears and approximately $15,000. A Phase I1 extension t o determine range l imitat ions f o r the scheme should be a program of approximately l i k e magnitude. Costs of Phase 111: f i n a l checkouts including more complex alignment apparatus fo r t he la rger pipe s izes a re indeterminate a t t h i s time. Work f o r t h i s phase should be combined with fu l l - sca le mockup schemes of ac tua l component ins ta l la t ions , which would e n t a i l considerable manpower, material, equipment, and re la ted costs.

3.13 Weld Preparation and Tack Welding of Pipe Jo in ts

3.13.1.1 Conce t; and Experience. d 3 e d " weld metal r ings tha t a r e in tegra l ly attached t o t h e pipe s tubs of t he replacement component, o r t o t h e replacement pipe. 2 3 A "buttered" r ing i s prepared by deposit- ing weld metal around t h e pipe stub i n t e r i o r and then machining t h e deposit t o a washer shape. The in t eg ra l weld metal r i ng i s : shaped and spaced t o simulate a Kelloggitype rectan- bular r ing consumable inser t . washer i s t o be made t o match the mating in -ce l l pipe end by using templates made from wax impressions. The washer shaped pipe end o f f e r s t h e addi t iona l advantage of having a f a i r l y r i g i d end configuration capable of withstanding moderate abuse during pipe handling operations. positioning, however, i s c r i t i c a l . The prepared end shape of t h e in -ce l l pipe sect ion consis ts of a nominal 1/16-inch root face and a bevel angle. hence vulnerable t o nicking o r deformation with bumping o r other improper pipe handling. It i s desirable t o attempt t o contact t h e jo in t face only i n a butted plane. It may become necessary t o temporarily protect t he in -ce l l pipe-joint ends with bumper shields u n t i l a replacement component (with i t s in t eg ra l pipe stub ends) i s lowered t o f i n a l elevation.

A t present it i s proposed t o use

The f i n a l machining of t he

The f i n a l pipe alignment

This rootface i s comparatively flimsy;

The in t eg ra l r i ng and stub w i l l be tack welded t o t h e in-ce l l pipe using t h e automated o r b i t a l pipe welding equipment as soon as proper alignment i s obtained. All aligning machinery mu,st remain energized f o r t he tacking operations t o clamp and r e s t r a i n t h e pipe sections and thereby firmly seat

34

t h e pipe ends. t he breaking of tacks a f t e r r e s t r a i n t removal, or during root- pass welding. ca te t ha t t he above procedure can be made t o work properly. 23'25

Suff ic ient tacks must be placed t o avoid

Preliminary f e a s i b i l i t y t r i a l s seem t o indi-

3.13.1.2 Future Development Requirements. To be discussed under Sec- t i o n 2.14.1, "Closure Welding - Pipe Welding".

3.14 Closure Welding

3.14.1 Pipe Welding

3.14.1.1 Ex erience. The ORNL automated welding f e a s i b i l i t y study *a follow-up report on f i r t h e r weld development with the ORNL system,25 and a report on automated o r b i t a l welding with recent ly avai lable commercial equipment systems, as well as an ORNL film on Automated Welding,27 a l l describe automated o r b i t a l welding operations i n considerable de ta i l . Some consideration was given t o adapting t h e o r ig ina l ORNL equipment f o r remote application, however, essent ia l ly no proper scale demonstrations were attempted, and t h i s s t i l l remains t o be done. It i s now a lso important t o monitor t h e progress of t he newly avai lable commercial automated o r b i t a l welding systems. 25'26 Five companies s t a r t ed market- ing such equipment i n 1972. machinery extensively fo r the pipe system construction of LMFBR f a c i l i t i e s . f'uture maintenance welding experimentation with these commercial systems t o u t i l i z e trained, knowledgable operators and qual i f ied welding and inspecting procedures.

2 6

The AEC i s planning t o use such

It may become appropriate t o conduct

The ORNL automated equipment consis ts of an "orbi ta l" carr iage t h a t clamps onto a pipe and propels t h e welding apparatus around the circumference of t he pipe. The carriage accommodates interchangeable heads fo r cu t t ing pipe o r f o r making tungsten inert-gas-arc welds. There i s an automatic welding programmer-controller t ha t constantly maintains a l l conditions necessary t o produce high qua l i ty welds. There i s a l so a hand operated pendant un i t t o provide a l t e rna t ive s t a r t and stop controls. To begin automated welding, an appropriate procedure i s dialed in to t h e programmer-controller, a button i s pushed, and the machine takes over t o produce t h e weld and then shuts i t s e l f off . A recorder coupled t o t h e system i s used t o record the major welding parameters including current, a rc voltage, carriage speed, wire feed r a t e , and s t a r t and stop. Figures 10 and 11 show the welding system.

3.14.1.2 Future Development Requirements. Automated welding i s now operational f o r d i rec t pipe welding i n construction applica- t ions. 26 $40,000 t o automatically butt-weld pipes from 3 t o 36 in. diameter and f o r wall thicknesses of 3/16 t o 1 1/2 in.

Commercial equipment systems a re now marketed below

The

35

W

i

PHOTO Y-106815

Fig. 10. ORNL Orbital Welding System

!x-ranpl_hce I ORNL DWG 73-2395 -. ,u"

I 4 i I

Fig. 11. Equipment Hook-Up, ORNL Weld System-

x

37

3.14.1.3

machines 0rbj.t t h e pipe f o r welding. Welds produced meet ASME and RDT Code Standards f o r nuclear-quality gas-tungsten- a rc welding of pipe. The commerical machines for t he present must be manually mounted on pipes, and operator understanding and judgment a re required f o r t he setups. The ORNL o r b i t a l carr izge and automated welding equipment can be in s t a l l ed remotely and operated from a remote s ta t ion.

Cost Ektimates. There i s a cho:ice of custom building individ- u a l ORNL type systems one a t a time a t roughly 1 1/2 t o 2 times the costs of t he commercial mass produced systems, or of attempting t o dhvise means and procedures t o adapt and con- ve r t t h e commercial machinery t o remote control applications. Since most nuclear piping systems w i l l probably be b u i l t with automated welding equipment by t h e l a t e 1970's, it i s recommended t h a t t h e commercially avai lable equipment be adapted f o r remote control operation. It i s estimated t h a t two manyears of e f f o r t plus $40,000 f o r supporting services and materials w i l l be required i n addition t o purchase of a commercially avai lable automated welding system, estimated t o cost $38,000.

The note of caution, however, must be repeated. A s with t h e pipe cu t t ing and beveling equipment, a l l present materials of construction f o r e i the r t h e ORTXL o r t h e commercial welder w i l l not withstand environmental- temperatures i n excess of 300°F and ma;y not hold up f o r an acceptable l i f e i n rad ia t ion f i e lds of 10 R/hr. A program must therefore be sponsored t o deve1o.p subs t i tu te materials, t o conduct f i rnace t e s t s , and thereaf te r , t o bui ld prototype weld heads f o r t o t a l weld system checkout i n su i tab le high-temperature t e s t ce l l s . Est i - mating cost:; for t h i s work would be premature and w i l l be develo,ped when environmental conditions are s e t more firmly, and a f t e r t he establishment of t he remote handling capabi l i ty f o r coinmercrial w e l d e r s .

--

3.14.2 Seal Welding

3.14.2.1 Description. Seal weld closures were i l l u s t r a t e d and d i s - cussed i n Section 2.5.2. W e expect t h a t t he welding head used i n O m , experiments, or a commercial head of equivalent design,, could be adapted t o follow the c i rcu lar path of t h e s e a l perimeter by at taching the head t o t h e end of a j ib- boom, which i s centered on t h e vesse l flange, as shown i n Fig. 12. Adaptive controls w i l l be used t o properly loca te t h e torch and t o adjust t h e torch-tungsten posit ioning f o r minor geomet,rical contour i r r e g u l a r i t i e s and/or minor f i t u p inconsistencies of mating sea l members. For s e a l welds on the s ide of t h e vessel, it i s possible t o support t he same type weld head from a carr iage t o r ide a r a i l t rack about t h e perimeter of a vessel , as i l l u s t r a t e d i n Fig. 13. We have completed a concept study f o r a crawler-carriage t o

3%

For CUPllINOt

Use s i r or e l e c M c cuttftq tools, e;l.snders, plasma torch, &/or gouging torch

Fig. 12. Conceptual Diaphragm or Sandwich Seal Weld with ORNL Weld Head Supported from a Motorized Carousel Linkage

39

I

I

Fig. 13. Flanged Vessel Seal Weld Closure Scheme f o r Orbital System Inser t s

3.14.2.2

r ide a s e t of s e a l l i p s as shown i n Fig. 14* The f i n a l design f o r s e a l weld closures w i l l govern t h e select ion of t he type of carr iage t o be used with a weld head Ghich i s common t o other systems.

Future Development Required. weld-head propulsion schemes a re needed f o r s e a l weld appl icat ions. Presently avai lable weld heads from t h e commercial systems can perform t h e he l ia rc s e a l welds required and t h e heads need only t o be adapted f o r remote control and automated s e a l welding operation. It i s reasonable t o assume tha t t h e weld heads developed f o r pipe welding could be used interchangeable i n the s e a l welder.

New types of carriages and

3.14.2.3 Cost Estimates. Approximately three manyears and $40,000 should be budgeted i f t h i s work can be performed i n conjunc- t i o n with recommended item 2.5.2, "Seal Weld Cutters" development. equipment s t ipu la t ions l i s t e d under item 2.14* 1, "Closure Welding - Pipe Welding" again a l so apply f o r s e a l welding equipment.

The special high-temperature and high-radiation

3.15 Inspection and Acceptance Tests

3.15.1.1 Concept and Experience. The technology of remote inspection and acceptance t e s t i n g by means of t h e more conventional penetrant checks, radiography and sonic inspection i s described i n the report "Remote Inspection of Welded Joints", ORNL-TM-3561, September 1971, by R. W. McClung. In addition, it now appears t h a t it may be possible t o evaluate the data recorded as the weld i s being made and from t h e data t o determine the l ikelihood of a flaw i n each weld pass. It i s known, from experience, t ha t excessive a rc voltage and low current w i l l cause lack of weld penetration; low arc voltage and high current, o r low wire feed and high weld current w i l l cause melt-through; high wire feed and low weld current w i l l b a l l t he bead; inconsistent carriage t r a v e l and hence, uneven weld speeds w i l l r e su l t i n uneven bead depth and contour; etc. The Recorder shown with t h e welding system i n Figures 10 and 11 charts welding current, a r c voltage, carr iage speed and wire feed ra te . The charted record can be compared t o previously prepared acceptable standards. If a l l p lo ts f a l l within predetermined allowable band-widths, t h i s i s evidence of a good weld. any two of t h e charted f'unctions should cause concern. (Single plot deviations usual ly indicate instrument Cali- bration, or s igna l noise f luctuat ions. ) Usually, a carefu l v i sua l inspection, with the char t ' s time scale used t o cal- culate t he spec i f ic locat ion of t he suspected flaw, w i l l confirm a weld defect. It i s hoped tha t t h e Code wr i te rs and t h e inspection agencies w i l l amend t h e i r present inspection pol ic ies t o permit t h e subs t i tu t ion of information

Simultaneously incurred i r r e g u l a r i t i e s t o

41

o

zl i: 4

ffi 0

a-

&$

42

from recorder charts f o r those Code requirements t ha t cannot be established with r e l i a b i l i t y by remote means.

3.15.1.2 Future Development Required. Recommendations f o r f i t u r e development work on remot e inspect ion and acceptance t e s t s a r e contained i n McClung' s report on "Remote Inspection of Welded Joints" .

43

APPENDIX A

CALCULATIONS FOR fYNTICIPATED MAXlMuM DEFLECTIONS AND RESTORATION FORCES FOR CUTTING INOR-8 PIPING MATERIAL

In considering t h e problems of remote maintenance on molten s a l t reactor systems, we have been concerned about how pipe ends might move or spring apart a f t e r a cut i s made t o remove some component which i s t o be replaced. The weight of components and of t he pipe i t s e l f w i l l impose s t r e s ses as w i l l thermal expansion o r thermal cycling a f t e r t h e system was ins ta l led . s h i f t o r def lect a f t e r a cut has been made. To be able t o rea l ign t h e pipe and hold it i n posi t ion f o r rewelding w i l l require some sor t of clamping mechanism which w i l l have t o be designed t o overcome the forces exerted on the pipes. pipe t o i t s o r ig ina l posi t ion pr ior t o realigning and rewelding t h e replacement component i n to t h e system.

One can an t ic ipa te t h a t the pipe ends w i l l surely

Force w i l l a l so be required t o res tore the cut

Two pipe layouts have been analyzed t o obtain an approximation of t he magnitude of t h e problem. The cases a re somewhat simplified and idealized t o permit ready analysis, but t he calculated def lect ion values should nevertheless be reasonable approximations. In any event, with standard supports and braces fx- the components of t he system, t h e calculated s t r e s ses on runs of pipe a re such as t o cause the cut ends t o def lect about an inch or less, not as much as a foot o r so. This information i s important i n determining what sor t of equipment w i l l be needed for aligning and holding pipes t o be rewelded. The cases tha t were analyzed were selected t o i l l u s t r a t e t he e f f ec t s of pipe length and pipe diameter on the magnitude of the def lect ion when a cut i s made. The calculations of t h e amount of def lect ion and the forces required t o res tore the de- f lec ted pipe t o i t s or ig ina l posi t ion indicate values tha t we can l i v e with,provided t h a t we use proper foresight i n es tabl ishing t h e system design t o meet reasonable requirements f o r fu ture maintenance.

Calculat ions

For a molten salt; reactor system operating near 1300°F over a three- year period, we have calcul.ated t h e maximum deflect ion of pipe ends a f t e r cu t t ing and calculated t h e forces required t o res tore the pipe ends t o t h e i r o r ig ina l posit ion. These calculat ions a re based on t h e assumption t h a t t h e system piping was or ig ina l ly in s t a l l ed so t h a t s t resses were within those established by t h e c r i t e r i a of Code Case 1315. The following paragraphs and i l l u s t r a t i o n s describe t h e calculations t h a t were performed and show t h e r e s u l t s t ha t were obtained.

Given :

1. Maximum permissible creep r a t e : Code allowable ma.ximum = 1% i n 100,000 hrs

= .26$ in 3 years

44

2. Assume:

a ) the uniform creep r a t e conservatively w i l l not exceed 50% max. N 1/7 of t he maximum thermal expansion).

there i s no s t r e s s i n the pipe a t assembly.

Select a uniform creep r a t e of .13% ( t h i s represents

b )

3 . Calculat e :

a ) Pipe Shi f t s vs. Pipe Lengths f o r

1) A typ ica l piping arrangement; both ends of t h e pipe run a re f ixed; no permanent pipe end support guides a t cut point.

2 ) A typ ica l piping arrangement; both ends of t he pipe run a re fixed; t he fixed pipe end supports include a common fixed base with guides on each s ide of t he pipe cut t o r e s t r a i n the pipe being cut.

b ) The magnitude of the res tora t ion force t o be applied t o the cut pipe ( f i r s t case) t o re turn the pipe t o i t s precut location.

1) Force vs. Pipe Length

2 ) Force vs. Pipe Size

45

CASE WITHOUT GUIDES PIPE SHIFTS VS. PIPE LENGTHS

a f t e r cut I f

I r v

t a before cooldown

1

cp = angular s h i f t a t cut

& = l i n e a r s h i f t a t cut-horizontal plane

Ay = l i n e a r s h i f t a t cut-vertical plane

& = t o t a l l i n e a r s h i f t - - _ -

- - 1 = p a r t i a l pipe length*

CP = 0 f o r piping arrangement shown

I u3

= 0.0013 ( A + 3 0 )

& = 0.0013 (2 + 30)

& = & Az = W 2 4- &T2

PIPE LE1\TGTH* 5' + 2'6" = 7'6"

10' + 2'6" = 12'6"

15 ' + 2'6" = 17'6"

20' + 2'6" = 22'6"

LINEN? PIPE SHIFTS AT CUT

&, & = 0.117" AZ = 0.17"

b, & = 0.195" Az = 0.28"

b, & = 0.273" AZ = 0.38"

b, Ay = 0.351" AZ = 0.50''

*Pipe lengths were selected t o correspond t o lengths used f o r t h e Case With Support Guides where t h e +2'6" i s t h e dis tance between f ixed end supports, with the pipe cut made 6" from t h e r e a r support f i x tu re .

46

CASE WITH SUPPORT GUIDES

P I P E S H I F T S VS. P I P E LENGTHS

before cooldown

c R" - cp = angular s h i f t a t cut

& = l i n e a r s h i f t a t cut, v e r t i c a l plane

&x = l i n e a r s h i f t a t cut, horizontal plane

fjy = resul tant sh i f t , a f t e r cut, Y-plane

R = p a r t i a l pipe length*

#- GUIDE

T = sin-1 for pipe arrangement shown

Ax = hx' + [ ( a + 2 4 ) - ( A + 24) cos cpl Where &x' i s Ax for case without guides.

Sy = 0.0013 - (30 + A ) 4 1 cp = sin-'

&x = 0.0013 (30 + R) + [ A + 24 - R + 24 cos c p ]

[: 3 term z O .*. &x = .0013 (30 + R ) P I P E LENGTH* ANGULAR AND LINEAR P I P E S H I F T S

5' + 2'6" = 7 '6" 0" -4' 0.117" 0 0.117"

10' + 2'6" = 12'6," 0" -4' 0.195" 0 0.195'' 15' + 2'6'' = 17'6" 0" -4' 0.273" 0 0.273"

20' + 2'6" = 22'6" 0" -4' 0.351" 0 0.351"

cp ax & 6Y

47

RESTORATION FORCE VS. PIPE SIZE AND LENGTH

Ay = l i nea r l i n e slnift R = p a r t i a l pipe length* W = force t o r e s to re 1 = moment of i n e r t i a E = modulus o f e l a s t i c i t y

i 6" Sched. 80

t ,----. m

Pipe

ay

W

(. 432 wall )

-1/3WR3 E 1

- 3 E I & A j

= 40.49 A = 8.405 20" Sched. 80 Pipe (1.031 wal l ) 1 = 2599.07 A = 61.440

Force W t o res tore: (W i s t he force required t o re turn the pipe i t s precut posit ion. )

6" Sched. 80 Pipe 20" Sched. 80 Pipe PIPE LENGTH W (pounds) W (pounds) 5' + 2'6" = 7'6" 760 49,000

10' + 2'6" = 12'6" 250 16,200

15' + 2'6'' = 17'6" 125 8,000

20' + 2'6" = 22' 6" 75 4,750

49

APPENDIX B

PROPOSAL FOR D!WELOPMENT OF A SPLIT-BEARING-SLEEVE CARRIAGE FOR REMOTE MAD!?TENANCE APPLICATIONS I N NUCLEAR REACTOR SYSTEMS

We recommend the buil-ding and t e s t i n g of a more r i g i d gear-driven carr iage t o supplement our present f l ex ib l e horseshoe-shaped f r i c t i o n - ro l le r -dr ive carriage. The gear-driven carr iage could be used t o advantage f o r increased torque capacity remote cu t t ing and beveling work, f o r highest t racking accuracy needs, and f o r i n t e rna l pipe cleaning appl icat ions. The subs t i t u t e carr iage consis ts of a s p l i t sleeve which i s supported by s p l i t r o l l e r bearings on each end. A motorized sp l i t -gear t rack i s attached t o one of t h e end bearings t o o rb i t t he sleeve about t he pipe.

The sp l i t - s leeve carr iage might a l so provide a simplified solut ion t o pipe alignment problems. It i s recommended t h a t a determination be made t o e s t ab l i sh how much i n i t i a l pipe displacement can be withstood by a sleeve supported on s p l i t bearings. This w i l l show whether t he s p l i t - bearing-sleeve can be used f o r remote maintenance pipe cu t t ing needs f o r some of t h e reactor service pipe l i nes . A t e s t program i s suggested to ascer ta in f e a s i b i l i t y , t o seek the pipe s i ze l i m i t s f o r which spl i t -bear ings a r e capable of t ransni t t i r ig moments, and t o compare t h e non-conventional approach t o more commonly accepted alignment technology based on r e s t r a i n t s attached to loose pipe ends.

Maintenance opeyations with spli t-bearing-sleeve equipment a r e exampli- f ied below:

1. Sk. 1

- -&-

I X I

Determine where to cut pipe r e l a t i v e t o t h e replacement componentDs prefabricated end stu.b (dis tance x'); l oca t e and a t t ach s p l i t bearing B* t o pipe accordingly (dis tance x); bearing B includes a preassembled s p l i t f ron t bushing guide. (The s p l i t bearings might include a so f t mater ia l or knurled bushing sleeve t o f i t ins ide t h e inner race f o r b e t t e r attachment to t h e pipe and t o make allowance f o r probably out-of-roundness of t he pipe. Otherwise, one must consider two separate funct ional devices, one t o f i rmly clamp the pipe and one t o center t he bearing on the pipe. The l a t t e r could be i n form of on attachment to t h e pipe clamp.) *Stocked Split-Roller-Bearings a r e commercially avai lable from t h e Cooper

S p l i t Roller Bearing Corporation, Pit tsburgh, Pa., and from other bearing manufacturers on spec ia l Drder.

50

2. Sk. 2

Inser t t h e lower half of bearing A with a s p l i t gear sector attached t o t h e bearing front face in to a locat ing cradle. about bearing B. Next, place t h e top half of bearing A, with i t s top gear section preattached, t o mate t o i t s lower half . Now permanently i n s t a l l bearing-gear assembly A t o t h e pipe.

Posit ion t h e cradle

Remove t h e locat ing cradle.

3. Sk. 3

I n s t a l l a cradled motor assembly ahead of gear-bearing assembly A. Check t h e adjustment of t h e cradle during t ightening t o ensure f r e e rota- t i o n of t h e bearing. I n s t a l l t h e s p l i t sleeve. Test dr ive t h e sleeved assembly. module with i t s sawblade,or t h e weld head module with i t s torch. could a l so include hosed pressurization, or vacuum exhaust, f o r chip d i s - posal o r accumulation. system's power and control cables t o t h e drive gear motor and t h e module inser t . (It i s possible t o eas i ly adapt t he balance of ORNL's automated o r b i t a l weld-cut system f o r t h i s application. )

The s p l i t sleeve contains a la rge cavi ty t o f i t a cu t t e r head It

I n s t a l l t h e cu t t e r head and connect t h e o r b i t a l

rr,

51

4. Sk. 4

Typical External I

ELEVATION VIEW Heater

Let us assume we have cut through the pipe t o remove t h e replacement component and t h a t t h e bearing supported maintenance sleeve assembly i s s t i l l attached. It i s qui te l i k e l y tha t a sh i f t w i l l occur i n the piping upon severing each l ine . This s h i f t would be most pronounced f o r the f r e e end of t h e permanent pipe as t h e component i s usual ly anchored and i t s short stubpipe locates t o t he anchor support. With the pipe sh i f t , t h e sleeve may now be placed i n s t r a in ; i n fac t , it i s doubtful t h a t t h e sleeve would then be rotatable . S t ra in gauges attached ax ia l ly t o t h e sleeve's ex ter ior would be used t o indicate t h e magnitude and the direct ion of pipe s h i f t . t o permit s t ress-rel ieving. The building crane could be u t i l i z e d fo r d i rec t up pul l , o r i n combination with s l ings, pulleys, etc. f o r required pipe movements i n other planes. Eventually, sleeve ro ta t ion could then be re- established and f i n a l precis ion pipe s h i f t adjustments could then be made l ikewise a f t e r i n se r t ing and observing d i a l gauges attached t o sleeve bosses on each s ide o'f t h e pipe cut- l ine f o r guidance. We could t r ans fe r pipe s t r e s s concentrations away from the pipe cut locat ion and thereby rea l ign t h e pipe ends formed by t h e cut t o assure near concentric pipe alignment f o r t h e stub end of t he replacement component. The ensleeved s t r e s s - r e l i e f approach which al igns pipe ends p r io r t o component removal should es tab l i sh useable pipe alignment f o r subsequent reassembly. Dangers from banging i n t o (and upset t ing) f r a g i l e weld j o i n t contours on the pipe ends a re minimized where the pipe f i t u p i s established pr ior t o removing one of t h e pipe jo in t members and subsequent re-entry i s with an iden t i ca l pipe. The maintenance sleeve i s dissambled from t h e jo in t p r ior t o component removal. We would resor t t;o more conventional pipe realigning means if a sleeve and/or i t s bea:rings a re permanently damaged as a r e su l t of excessive pipe moment force act ion upon severing t h e pipe.

Heat could be applied t o t h e permanent piping i n selected locations

52

5. End Preparations and In te rna l Pipe Cleaning

Sk. 5

M

a k 9 .a

V

The regular maintenance sleeve and the component, including i t s pipe stub with end bearing 'B' , have been removed.

Attach an a l t e rna te s p l i t sleeve t o the remaining bearing ' A ' - gear-motordrive while it i s s t i l l i n s t a l l ed near t he end of the permanent i n -ce l l pipe. The a l t e rna te sleeve includes in t e rna l wide- bearing i n s e r t s i n locat ion ' C ' . This sleeve can be b u i l t t o accom- modate the ORNL machining head module for preparing a beveled pipe end. As t h i s sleeve i s self-propelled, it may a lso include provisions for at taching the equipment needed for a l l i n t e rna l pipe cleaning.

53

6. Reassembly

Sk. 6 (Upper)

c

Reassembly problems d i f f e r f o r various components and depend upon avai lable a x i a l room f o r entry of t h e component with i t s pipe s tub(s ) . A guided entry u t i l i z i n g the 'B'-bearing tapered sleeve-guide i s preferred i f space i s available. The s p l i t 'B'-bearing-guide-sleeve combination i s preassembled on t h e replacement component's stub-pipe end while t he component i s out of t he ce l l . The s p l i t maintenance sleeve would be r e ins t a l l ed over the 'A'-bearing pr ior t o i n s t a l l i n g the replacement component. The component would be f i r s t lowered t o a f i n a l elevation support platform and then scooted in to place while guiding the pipe stub in to the funnel end of t he sleeve. The sleeve would guide t h e pipe stub in to i t s proper locat ion r e l a t i v e t o the in -ce l l pipe

--

ion clearance

-__ - - -

Sk. 6 (Lower)

For t h e case of only v e r t i c a l access f o r a replacement component, pipe ends would have t o be butted. with Sk. 2 would apply.

The cradle assembly scheme described

After assembly of t h e component by e i the r scheme, t he rewelding of t h e pipe ends would be accomplished with the weld head module in s t a l l ed in to t h e sleeve cavity.

55

REFERENCE INFORMATION

, I

OP HALF HOUSING

-- HALF OUTER RACE

-- HALF CAGE WITH ROLLERS

CAGE JOINT “U” CLIPS

L__ ___ TWO HALF CLAMPING RINGS

_-__--- - HALF INNER RACE

1.. , “+I --. ____------- HALF INNER RACE

’ - -

-l.-,a -d

-----% ~, TWO HALF CLAMPING R i H G j a. I / - ___ --.------------- -----

HALF CAGE WITH ROLLERS

CAGE JOINT “U” CLIPS

HALF OUTER RACE

HALF SEAL

BOTTOM HALF HOUSING

PEDESTAL BASE

56

REFERENCE INFORMATION

P R O C E D U R E

I Loosen holding bol ts and remove top hol f of pedestal and top hol f of cn:rri ige hauzin;. i i i t out ro i ier c i s a m b l y cnd inner race. Withdraw spring steel "U" c l i p s on opposite sides of roller ossombly. Ssporoto halves of rolI*r assembly and put to one r i d e - loy on c l a m place of

pope,. Remo,s the lour bolts hold ing the clamping collors around the i*i .cr rote - mmk* a w e to keep the mating halvos of clomplng collrrrs to ja thrr . S s p o m t e the halves of the inner race and wmsh thoroughly wi th gooJ :leaning solvent and dry wi th l i n t - f r e e wip ing moterial 01 let stond u n t i l completely dry. 1. the same mannmr, c1.m and dry the clamping co!lil;s, both halves of the ro l le r oss.mbly and the outer roc*. I t i s not n-ce isory 12 remova the outer roc, from the cartr idge housing t o claon it. (If eve . nectssory t o remove the outer race, first make sur0 thot all rid. n ipp ing -screws and holding back-screws whsrs f i t ted era removed.)

2 For normal stmody load sarvic.. the shaft must be of nominal s izo wi th in th. l imits of plus 0.000" to minus 0.002", and cy l indr ica l ly true. Clean ond l ight ly o i l th- area of the shmft t o receive the inner race and place the two halves of the inner rase i n the prop., a x i a l location. T a p the holrss of the inner race u n t i l secure and snug on the shaft. NEVER H I T THE RACE WITH A HAMMER OR OTHER HARD M E T A L L I C TOOL. USE WOOD OR PLASTIC MALLET. There should be a s l ight gop ot both andl of the h.1v.s of the inner race. Put clamping collars i n place, moking sure they f i t snugly ogoinst the race shouldor. c lamping cel!or io in t should overlap the race jo in t by obout Vi'' t o H" on E x - ponsion Typ. Bearing.. The omount of ovstlap i s oxtremmly important for the f i t ted clamping collar of f ixed t i p innor races. It w i l l b. noted thar.

is nn air01 on th is col lar which must coincide w i t h the morkod race ioint. This ensures the alignment of th. shouldorr of the inner race. Us. locking worhorr under the heods of the clamping collar bolts, ond r t n r t t o tightel, tnom, but before f ina l t ightening of bolts, check a x i a l location of inner rote to mako SUI* i t i s i n th. correct posit ion on the shaf t so that i t w i l l ba central wi th the rest of the uni t w h m oss.mb1.d. In cases where ox io l expansion has to be handled, the inn., roc. i s offsot so that s ( t cr f u l l expansion of the s h d t hos taken ploce, the races and r o l l i n g elements w i l l 0 1 1 be central with on. another. A l s o check to mak. sur*

th-t the t w o hol res of the inner race aro NOT TOUCHING soch other, m d thot the s l ight gap is approximately aqvol on both sides. The gap i s pu,poroly bui l t in to tho bsoring, and shovld thoro bo N O qap, the s h o h i s vdn'.rsizo which wil l rorult in unsatisfactory pwformonco. If the shaft i s within the required l imits, the propor omount of gap i s automoticolly present when the clamping collors are f ina l ly tightnned. Now f in ish tig'itening of clomping E O I I O V bolts, using D pioc. of pip. on tho socket w:.nch t o c a k e sure they nro cbrolutmly tight. Sso Torque Tobls on p,>gs 12. A l l f ~ v r bol ts should be pul lod up evenly when t ightening th. i ~ n ~ r race on the shaft. In the sx,pnsion typ. unit, check both clamping rings t o si* t i o t they ore hord against th. race shoulder al l around. I n rke COJI of the f ixad unit, check the and clomping col lar t D make sure i t is hard o y i n i t the shoulder 011 around.

c) P l r c s bottom hal f of ped.=tal i n posit ion and l ight ly o i l the 3 p h . r -

i c i l scot for tho cortvidge. T h s posit ion of th. bottom hol f of cartr idge w i l l determine on which sid. of pi l low block the greoro f i t t ing w i l l bo for lubrication. Toke car= t o locat. bottom hol f of cortridg. so thot greaa.

f i t t ing i s eosi ly occesr ib lo . I f th. bearing i s to be lubricotod by grease, opply the required quonti ty ins ide of the lower hal f o f the cartr idge w i t h the hal f outer roce i n posit ion and then ploce i n the bottom hol f of the pedestal. Jnck up the shaft r l ightl ; i f th is hos not olreody beon don..

Toke hol f LI rol ler assembly, graas. we11 e l l over i f beoring i s t o bo lubricated by grsas., and then ploce on inner rmce and slid. rrrovnd u n t i l i t is s i t t i n g on the bottom hmlf outer race, w i t h the ends of the cog. f lush wi th the housing jo in t face.

4 Rsmovo locking pins (2) from soch aluminum t r ip le lobyrinth real and place sa01 around shaft i n corwct posit ion w i t h rs lo t ion to cartridg. groove, and reinsert locking pins. T h e seals, w h m correctly ossembl.d, w l l l gr lp the shaft f i rmly and r.voIvo with i t but w i l l permit axla l m e w -

men? of the s h o h w h m n.c.asary.

5 Remove iocking orrmgmment, o l l o r i n g shaf t t e rest .v.nly in the baoring.

6 Greos. the remaining hal f rol ler ossembly oII over (wi th fo i r ly heavy coot) and ploce over exposod part of innev IOCO. R-plase spring "U" c l i p s by l ight ly topping into recess.i i n rollet pockets, thus lock ing tho halves of the roller assembly together.

7 Grms. w i t h the required omount, the inside of top h a l f of cartr idge wi th ho l f out.* race i n posit ion. Make sure the io in ts of th. cartr idge housing, both t o p end bottom halves, ore absolutely c h o n beforn apply - ing greoss. Place top hal f of coltr idge in to pos i t ion over oss.mb1.d bearing end sools moking sure thmt jo in ts match the bottwn half. Us. locking washers on bolts ond t ighten up evenly 0 1 1 four bol ts in cortridg-. Moks sura end focsr of cartr idge are f lush when com?let . ly t i g h t e n d .

8 Apply a c w t i n g of o i l on the spherical seat of the tap hol f of the pedestol ond place i n position, but d o not tight." u p bolts.

9 I f possible, turn shaft s lowly two or three times t o permit the cortridg. t o f ind i ts own ol ignment so that the logding of the roller. i s evenly distr ibutsd. I f th is i s not pessibls, make s u r i tho? cartr idge fn:as

ore obsolutcly square wi th the shaft.

1 b i g h t e n up top hal f of unit. G l r e b o w i n g threa or four shots wi th

grease gun to f i l l the graos. passages so that noxt t ime th. bror ing i s gr.0s.d you w i l l b. SUI. that graos. i s g-tt ing t o the r o l l i n g par ts . Use discration when graoslng, according to s p e d and duty. 00 not o v e r f i l l w l th gnar., otherwise a "Hot Bear ing" may result.

11 O i l Lubricotion. Follow obore instruct ions except substi tute lubri ~

ca t lng o i l for gr.0~0. O i l level i n bottom h a l f o f cartr idge should b. o s

outl ined under O I L LUBRICATION on p g . 13.

S h o u l d further d e t o i l s be r e q u i r e d r e g a r d i n g f i t t i n g and lubrication of t h e becring, pleose contecr

COOPER SPLIT ROLLER BEARING CORPORATION

1725 Wa.hinglon Road, Pittsburgh, Pennrylvonia 15241

REFERENCES

1. R. W. McClung, Remote Inspection of Welded Joints , ORNL-TM-3561 (September 1971T.

2. J. S. Culver, Viewing Equipment f o r Use i n the HRT Core and Blanket Vessels, OIWL-rn36 (March 1960).

3. In te rna l Memo, P. P. Holz t o I. Spiewak, "Dry Maintenance F a c i l i t y f o r t he HRT", Oc-tober 11, 1960.

A 0 In te rna l Memo, J. P. Jarvis t o S. E. Beall, "Use of t he Dry Mainte- nance F a c i l i t y f o r HRT Maintenance", May 17, 1962.

5. P. P. Holz, "Remote Maintenance Through Portable Shields", ANS Winter Meeting, Pittsbui?gh, Pa., November 1966, (complete paper avai lable from author).

6. R. Blumberg and E. C. Hise, MSRE Design and Operations Report - Part X - Maintenance Equipment and Procedures, ORNL-TM-910 (June 1968).

7. Theodore Rockwell 111, Reactor Shielding Design Manual, Naval Reactors Branch, Division of Reactor Development, USAEC, Chapter 6, TID-7004 (March 1956).

8. R. C. Robertson, MSRE Design and Operations Report, Par t I, Descrip- t i o n of Reactor Design -9 ORNL-TM-728 (January 1965).

9. In te rna l Memo, B. D. Draper and E. C. Hise t o Distribution, "Remote Maintenance Procedures Report", November 26, 1959.

lo. In te rna l Memo, A. A. Abbatiello t o Distribution, "Optical Tooling f o r t he MSRE", June 4, 1962.

11. Correspondence, E'. P. Holz t o Distribution, "Trip Report t o BONUS, (Boiling Nuclear Superheater Power Stat ion) , Rincon, Puerto Rico , September 25, 1967 t o October 13, 1967','.

12. J. P. Maloney, e t a l , Repair of a Nuclear Reactor Vessel, DP-1199, Dupont Savannah River Laboratory (June 1969).

13. D. S. Ritchie, -. e t ,, a 1 "Remote Controlled Viewing f o r t h e Dragon React or Main Pres sur e Ves sell: Atomic Energy E s t ablishment England, Dragon Froject Report 228, October 1963.

Winf r i t h ,

14. R. N. Duncan and D. L. Richardson, F ina l Report on BONUS Reactor Boiler Fuel Element InsDection. October 5 ' to 12. 1967. ReDort APED-

.L L

5392 (Class I), Nuclear Energy Division, General E lec t r i c Company, - - _ San Jose, California, November 1967.

15. Conceptual Design of a Surveillance and In-Service Inspection System f o r t h e Reactor Vessel Fast Flux Test Fac i l i ty , Phase B Report, Chapter 3, Southwest Research Ins t i t u t e , San Antonia, Texas, Dec. 31, 1969, (report prepared f o r t h e Pacif ic Northwest Laboratory by t h e Bat te l le Memorial I n s t i t u t e ) .

16. Conceptual Design of a Surveillance and In-Service Inspection System for t he Primary Piping and Components, Fast Flux Test Fac i l i ty , Chapter 3, Phase C Report, Southwest Research Ins t i t u t e , San Antonia, Texas, January 16, 1970, (report prepared f o r t h e Pac i f ic Northwest Laboratory, Bat te l le Memorial I n s t i t u t e ) .

17. Internal Memo, P. P. Holz t o Distribution, "Miniature TV Camera Manipulator", ( for HRT viewing), November 26, 1959.

18. R. L. Moore, Closed Circuit Television Viewing i n Maintenance of Radioactive Systems a t ORNL, ORNL-TM-2032 (November 1, 1967), (paper a l so presented t o the ANS Winter Meeting, Pittsburgh, Pa., Nov. 1966).

19. M. W. Rosenthal, -- e t a l , The Development Status of Molten-Salt Breeder Reactors, ORNL-4812, Chapter 12 (August 1972).

20. In te rna l Memo, P. P. Holz t o Distribution, "Some Miscellaneous Mainte- nance Tools Used t o Manipulate Loose Objects i n the HRT Core", Nov. 17, 1959.

21. In te rna l Memo, P. P. Holz t o Distribution, "Additional Miscellaneous Maintenance Tools Used i n the HRT Core", September 26, 1960.

22. "ORNL Remote Maintenance Tool Catalogue No. 58", June 1960. (Compila- t i o n of t oo l s and procedures by the Mechanical Department, Engineer- ing and Mechanical Division. )

23. P. P. Holz, Feas ib i l i t y Study of Remote Cutting and Welding for Nuclear Plant Maintenance, ORNL-TM-2712 (November 1969).

24. R. F. Gilmore, Open- and Closed-Loop Closure Remote Cutting and Weld- ing Evaluation, Bat te l le Northwest Laboratory Report BNWL-1303 (UC-38) , May 1970.

25. P. P. Holz, The ORNL Automated Orbi ta l Pipe Welding Systems, ORNL4830 ' - qm----- *=

I -

26. G. M. Goodwin and P. P. Holz, Automated Orbi ta l Welding of Type 304 Stainless S tee l Pipe with the Astro-Arc System, O m - T M Report (d ra f t issue dis t r ibuted for comments July 1972. )

27. "Automated Welding", Film avai lable from t h e ORNL Film Library, 1971.

28. Pennsylvania Advanced Reactor Project - Layout and Maintenance, WCAP 1104 and 1105, Vol. IV, Par ts 1 and 2, Westinghouse Elec t r ic Corp. and Pennsylvania Power and Light Company, March 1959, ChaFters 3, 4, and 5 (chapter 4.2 for Alignment Discussions).

29. Molten-Salt Reactor Program Semiannual Progress Report f o r Period Ending Feb. 28, 1969, ORNL-4396, Chapter 5-MSBR Design (Aug. 1969).

-* 30. J. R. Tallackson, pr ivate communication t o R. W. McClung, Jan. 29, 1971.

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